Equus 3110 User Manual

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Table of Contents

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Title Page No.

INTRODUCTION

What is OBD? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

YOU CAN DO IT! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

SAFETY PRECAUTIONS

Safety First! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

ABOUT THE CODE READER

Vehicles Covered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Battery Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Adjustments and Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

CODE READER CONTROLS

Controls and Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Display Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

ONBOARD DIAGNOSTICS

Computer Engine Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Diagnostic Trouble Codes (DTCs) . . . . . . . . . . . . . . . . . . . . . . 20

OBD 2 Monitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

PREPARATION FOR TESTING

Preliminary Vehicle Diagnosis Worksheet . . . . . . . . . . . . . . . . 30

Before You Begin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

USING THE CODE READER

Code Retrieval Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Erasing Diagnostic Trouble Codes (DTCs) . . . . . . . . . . . . . . . . 40

I/M Readiness Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

GLOSSARY

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Glossary of Terms and Abbreviations . . . . . . . . . . . . . . . . . . . 49

WARRANTY AND SERVICING

Limited One Year Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Service Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Introduction

WHAT IS OBD?

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WHAT IS OBD?

The CAN OBD2 Code Reader is designed to work on all OBD 2

compliant vehicles. All 1996 and newer vehicles (cars, light

trucks and SUVs) sold in the United States are OBD 2 compliant.

One of the most exciting improvements
in the automobile industry was the addition
of on-board diagnostics (OBD) on vehicles,
or in more basic terms, the computer that
activates the vehicle’s “CHECK ENGINE”
light. OBD 1 was designed to monitor manu­facturer-specific systems on vehicles built
from 1981 to 1995.Then came the develop­ment of OBD 2, which is on all

1996 and newer vehicles sold in the
U.S.Like its predecessor, OBD 2 was adopted as part of a government
mandate to lower vehicle emissions.But what makes OBD 2 unique is
its universal application for all late model cars and trucks - domestic
and import. This sophisticated program in the vehicle’s main computer
system is designed to detect failures in a range of systems, and can
be accessed through a universal OBD 2 port, which is usually found
under the dashboard. For all OBD systems, if a problem is found, the
computer turns on the “CHECK ENGINE” light to warn the driver, and
sets a Diagnostic Trouble Code (DTC) to identify where the problem
occurred. A special diagnostic tool, such as the CAN OBD2 Code
Reader, is required to retriev e these codes , which consumers and pro­fessionals use as a starting point for repairs.

To learn more about vehicle Computer Control Systems and

OBD 2, see COMPUTER ENGINE CONTROLS on page 14.

You Can Do It!

EASY TO USE - EASY TO VIEW - EASY TO DEFINE

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Easy T o Use ....

■ Connect the Code Reader to the

vehicle’s test connector.

■ Turn the ignition key "On.”

■ Press the LINK button.

Easy T o View ....

■ The Code Reader retrieves stored

codes, Freeze Frame data and I/M
Readiness status.

■ Codes, I/M Readiness status and

Freeze Frame data are displayed on the
Code Reader’s LCD display screen.
System status is indicated by LED indi­cators.

Easy T o Define ....

■ Read code definitions from the Code

Reader’s LCD display.

■ View Freeze Frame data.

Safety Precautions

SAFETY FIRST!

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SAFETY FIRST!

This manual describes common test procedures used by
experienced service technicians. Many test procedures
require precautions to avoid accidents that can result in
personal injury, and/or damage to your vehicle or test
equipment. Always read your vehicle's service manual and
follow its safety precautions before and during any test or
service procedure. ALWAYS observe the following general
safety precautions:

When an engine is running, it produces carbon monox­ide, a toxic and poisonous gas.To pre vent serious injury
or death from carbon monoxide poisoning, operate the
vehicle ONLY in a well-ventilated area.

To protect your eyes from propelled objects as well as
hot or caustic liquids, always wear approved safety
eye protection.

When an engine is running, many parts (such as the
coolant fan, pulleys, fan belt etc.) turn at high speed. To
avoid serious injury, always be aware of moving parts.
Keep a safe distance from these parts as well as other
potentially moving objects.

Engine parts become very hot when the engine is run­ning. To prevent severe burns, avoid contact with hot
engine parts.

Before starting an engine for testing or trouble-shoot­ing, make sure the parking brake is engaged. Put the
transmission in park (for automatic transmission) or
neutral (for manual transmission). Block the drive
wheels with suitable blocks.

Connecting or disconnecting test equipment when the
ignition is ON can damage test equipment and the vehi­cle's electronic components. Turn the ignition OFF
before connecting the Code Reader to or disconnecting
the Code Reader from the vehicle’s Data Link
Connector (DLC).

To avoid personal injury, instrument damage and/or

damage to your vehicle; do not use the CAN OBD2 Code

Reader before reading this manual.

N

R

P

D

L

Safety Precautions

SAFETY FIRST!

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To prevent damage to the on-board computer when tak­ing vehicle electrical measurements, always use a digi­tal multimeter with at least 10 megOhms of impedance.

Fuel and battery vapors are highly flammable. To pre­vent an explosion, keep all sparks, heated items and
open flames away from the battery and fuel / fuel
vapors. DO NOT SMOKE NEAR THE VEHICLE DUR­ING TESTING.

Don't wear loose clothing or jewelry when working on an
engine. Loose clothing can become caught in the fan,
pulleys, belts, etc.Jewelry is highly conductive, and can
cause a severe burn if it makes contact between a
power source and ground.

About the Code Reader

VEHICLES COVERED

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VEHICLES COVERED

The CAN OBD2 Code Reader is designed to work on all OBD 2 com­pliant vehicles.All 1996 and newer vehicles (cars and light trucks) sold
in the United States are OBD 2 compliant.

Federal law requires that all 1996 and newer cars and light
trucks sold in the United States must be OBD 2 compliant;
this includes all Domestic, Asian and European vehicles.

Some 1994 and 1995 vehicles are OBD 2 compliant. To find out if a
1994 or 1995 vehicle is OBD 2 compliant, check the following:

1. The Vehicle Emissions Control Information (VECI) Label. This

label is located under the hood or by the radiator of most vehicles.If
the vehicle is OBD 2 compliant, the label will state “OBD II Certified.”

2. Government Regulations require that

all OBD 2 compliant vehicles must
have a “common” sixteen-pin Data
Link Connector (DLC).

Some 1994 and 1995 vehicles have 16-pin connectors but
are not OBD 2 compliant. Only those vehicles with a Vehicle
Emissions Control Label stating “OBD II Certified” are OBD 2
compliant.

Data Link Connector (DLC) Location

The 16-pin DLC is usually
located under the instrument
panel (dash), within 12 inches
(300 mm) of center of the
panel, on the driver’s side of
most vehicles.It should be eas­ily accessible and visible from
a kneeling position outside the
vehicle with the door open.

VEHICLE EMISSION CONTROL INFORMATION

ENGINE FAMILY EFN2.6YBT2BA

VEHICLE

MANUFACTURER

REFER TO SERVICE MANUAL FOR ADDITIONAL INFORMATION
TUNE-UP CONDITIONS: NORMAL OPERATING ENGINE TEMPERATURE,
ACCESSORIES OFF, COOLING FAN OFF, TRANSMISSION IN NEUTRAL

EXHAUST EMISSIONS STANDARDS STANDARD CATEGORY
CERTIFICATION

IN-USE

SPARK PLUG

TYPE NGK BPRE-11

GAP: 1.1MM

DISPLACEMENT 2.6L

THIS VEHICLE CONFORMS TO U.S. EPA AND STATE
OF CALIFORNIA REGULATIONS APPLICABLE TO
1999 MODEL YEAR NEW TLEV PASSENGER CARS.

TLEV
TLEV INTERMEDIATE

CATALYST

OBD II

CERTIFIED

OBD II

CERTIFIED

12345678
910111213141516

LEFT CORNER

OF DASH

NEAR

CENTER

OF DASH

BEHIND

ASHTRAY

About the Code Reader

VEHICLES COVERED / BATTERY REPLACEMENT

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On some Asian and European vehicles the DLC is located
behind the “ashtray”(the ashtray must be removed to access
it) or on the far left corner of the dash. If the DLC cannot be
located, consult the vehicle’s service manual for the location.

BATTERY REPLACEMENT

1. Locate the battery cover on the back of the Code Reader.

2. Slide the battery cover off (use your fingers).

3. Replace batteries with three AA-size batteries (for longer life, use

Alkaline-type batteries).

4. Reinstall the battery cover on the back of the Code Reader.

Language Selection After Battery Installation

There are two versions of the Code Reader: English/Spanish and
English/French.The first time the unit is tur ned on (after the batteries
are installed or replaced), you must select the desired display lan­guage, as follows:

1. Press the POWER/LINK button to turn the Code Reader “ON.”

■ The Select Language screen displays.

2. Use the UP and DOWN but-

tons, as necessary, to highlight the
desired display language.

3.

When the desired display language is
selected, press the ENTER/FF but­ton to confirm your selection.

■ The selected language will remain in

the Code Reader’s memory as long
as the batteries are not removed. If
the batteries are removed (or go
dead), the language selection will be
lost from the Code Reader’s memory
and must be reset again using steps
1 through 3, above.

■ After the initial language selection is performed, it as well as

other settings can be changed as desired. See ADJUSTMENTS
AND SETTINGS on page 7 for further instructions.

About the Code Reader

ADJUSTMENTS AND SETTINGS

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ADJUSTMENTS AND SETTINGS

The CAN OBD2 Code Reader lets you make several adjustments and
settings to configure the Code Reader for your particular needs. The
following adjustments and settings can be made:

■ Adjust Brightness: Adjusts the brightness of the LCD display

screen.

■ Demo Mode: Sample data kept in the Code Reader’s memory to

use as examples and for demonstration purposes.

■ Select Language: Sets the display language for the Code Reader

to English/Spanish or English/French.

■ Unit of Measure: Sets the Unit of Measure for the Code Reader’s

display to USA or metric.

Adjustments and settings can be made only when the Code
Reader is NOT connected to a vehicle.

To enter the MENU Mode:

1. With the Code Reader “off”, press and

hold

the UP button, then press and

release the POWER/LINK button.

■ The adjustments and setting MENU

displays.

2. Release the UP button.

DO NOT release the UP b utton until the adjustments and
settings MENU is visible on the display.

3. Make adjustments and settings as described in the following para-

graphs.

Adjusting Display Brightness

1. Use the UP and DOWN but-

tons, as necessary, to highlight Adjust
Brightness in the MENU, then press
the ENTER/FF button.

■ The Adjust Brightness screen dis-

plays.

■ The Brightness field shows the cur-

rent brightness setting, from 0 to 43.

2. Press the UP button to decrease

the brightness of the LCD display (make
the display darker).

About the Code Reader

ADJUSTMENTS AND SETTINGS

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3. Press the DOWN button to increase the brightness of the LCD

display (make the display lighter).

4. When the desired brightness is obtained, press the ENTER/FF

button to save your changes and return to the MENU.

Selecting the Display Language

1. Use the UP and DOWN but-

tons, as necessary, to highlight Select
Language in the MENU, then press the
ENTER/FF button.

■ The Select Language screen dis-

plays.

■ The currently selected display

Language is highlighted.

2. Press the UP or DOWN button,

as necessary, to highlight the desired
display language.

3. When the desired display language is

highlighted, press the ENTER/FF
button to save your changes and return
to the MENU.

Setting the Unit of Measure

1. Use the UP and DOWN but-
tons, as necessary, to highlight Unit of
Measure in the MENU, then press the
ENTER/FF button.

2. Press the UP or DOWN button,

as necessary, to highlight the desired

Unit of Measure.

3. When the desired Unit of Measure

value is selected, press the ENTER/FF

button to save your changes.

About the Code Reader

ADJUSTMENTS AND SETTINGS

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Demo Mode

1. Use the UP and DOWN but-

tons, as necessary, to highlight Demo
Mode in the MENU, then press the
ENTER/FF button.

2. The Code Reader enters the Demo

Mode.

3. Demo Mode demonstrates examples of Generic and Enhanced

(Manufacturer Speciific) Diagnostic Trouble Codes, code definitions,
Freeze Frame data and I/M Readiness status.

■ Use Demo Mode to familiarize yourself with Code Reader oper-

ation, vehicle diagnostic data and/or for demonstration purposes.

4. To exit Demo Mode, turn the Code Reader off by pressing the

POWER/LINK button.

Exiting the MENU Mode

1. Use the UP and DOWN buttons, as necessary, to highlight

Menu Exit in the MENU, then press the ENTER/FF button.

■ The LCD display returns to the DTC screen.

Changes made to Brightness, Language and Unit of
Measure will remain in the Code Reader’s memory as long
as the batteries are not removed.If the batteries are removed
(or go dead), the settings will be lost from the Code Reader’s
memory, and they must be reset again.

Code Reader Controls

CONTROLS AND INDICATORS

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CONTROLS AND INDICATORS

See Figure 1 for the locations of items 1 through 11, below.

1. ERASE button - Erases Diagnostic Trouble Codes (DTCs),
and “Freeze Frame” data from your vehicle’s computer, and resets
Monitor status.

2. DTC SCROLL button - Displays the DTC View screen and/or
scrolls the LCD display to view DTCs when more than one DTC is
present.

3. POWER/LINK button - When the Code Reader IS NOT
connected to a vehicle, turns the Code Reader “On” and “Off”. When
the Code Reader is connected to a vehicle, links the Code Reader to
the vehicle’s PCM to retrieve diagnostic data from the computer’s
memory.

4. ENTER/FREEZE FRAME button - When in MENU mode,
confirms the selected option or value. When retrieving and viewing
DTCs, displays Freeze Frame data for the highest priority code.

Figure 1. Controls and Indicators

11

10

7
6

1
2
5

8

9
3

4

Code Reader Controls

CONTROLS AND INDICATORS

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5. DOWN button - When in MENU mode, scrolls DOWN through
the menu and submenu selection options. When retrieving and view­ing DTCs, scrolls down through the current display screen to display
any additional data.

6. UP button - When in MENU mode, scrolls UP through the
menu and submenu selection options. When retrieving and viewing
DTCs, scrolls ups through the current display screen to display any
additional data.

7. GREEN LED - Indicates that all engine systems are r unning nor­mally (all Monitors on the vehicle are active and perfor ming their diag­nostic testing, and no DTCs are present).

8. YELLOW LED - Indicates there is a possible problem. A “Pending”
DTC is present and/or some of the vehicle’s emission monitors have
not run their diagnostic testing.

9. RED LED - Indicates there is a problem in one or more of the vehi­cle’s systems.The red LED is also used to show that DTC(s) are pres­ent. DTCs are shown on the Code Reader’s LCD display. In this case,
the Multifunction Indicator (“Check Engine”) lamp on the vehicle’s
instrument panel will light steady on.

10. LCD Display - Displays settings Menu and submenus, test
results, Code Reader functions and Monitor status information. See

DISPLAY FUNCTIONS, on next page, for more details.

11. CABLE - Connects the Code Reader to the vehicle’s Data Link

Connector (DLC).

Code Reader Controls

DISPLAY FUNCTIONS

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DISPLAY FUNCTIONS

See Figure 2 for the locations of items 1 through 16, below.

1. I/M MONITOR ST ATUS field - Identifies the I/M Monitor status area.

2. Monitor icons - Indicate which Monitors are supported by the vehi-

cle under test, and whether or not the associated Monitor has run
its diagnostic testing (Monitor status).When a Monitor icon is solid,
it indicates that the associated Monitor has completed its diagnos­tic testing.When a Monitor icon is flashing, it indicates that the vehi­cle supports the associated Monitor, but the Monitor has not yet run
its diagnostic testing.

3. Vehicle icon - Indicates whether or not the Code Reader is
being properly powered through the vehicle’s Data Link Connector
(DLC). A visible icon indicates that the Code Reader is being pow­ered through the vehicle’s DLC connector.

4. Link icon - Indicates whether or not the Code Reader is com­municating (linked) with the vehicle’s on-board computer.When vis­ible, the Code Reader is communicating with the computer. If the
Link icon is not visible, the Code Reader is not communicating with
the computer.

5. Computer icon - When this icon is visible it indicates that the
Code Reader is linked to a personal computer.An optional “PC Link
Kit” is available that makes it possible to upload retrieved data to a
personal computer.

6. Code Reader Internal Battery icon - When visible, indicates
the Code Reader batteries are “low” and should be replaced.

7. DTC Display Area - Displays the Diagnostic Trouble Code (DTC)
number. Each fault is assigned a code number that is specific to
that fault.

Figure 2. Display Functions

11 12

21

10

3
4
5
6

7
8

14
15

13

9

Code Reader Controls

DISPLAY FUNCTIONS

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8. Test Data Display Area - Displays DTC definitions, Freeze Frame
data, and other pertinent test information messages.

9. MIL icon - Indicates the status of the Malfunction Indicator Lamp
(MIL).The MIL icon is visible only when a DTC has commanded the
MIL on the vehicle’s dashboard to light.

10. CODE icon - Identifies the Code Number Sequence display area.

11. PENDING icon - Indicates the currently displayed DTC is a

“Pending” code.

12. Code Number Sequence - The Code Reader assigns a

sequence number to each DTC that is present in the computer’s
memory, starting with “01.” This number indicates which code is
currently displayed.Code number “01” is always the highest prior­ity code, and the one for which “Freeze Frame” data has been
stored.

If “01” is a “Pending” code, there may or may not be
“Freeze Frame” data stored in memory.

13. Code Enumerator - Indicates the total number of codes retrieved

from the vehicle’s computer.

14. Generic DTC icon - When visible, indicates that the currently

displayed DTC is a “generic” or universal code.

15. Enhanced DTC icon - When visible, indicates that the currently

displayed DTC is a Manufacturer Specific Code.

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Onboard Diagnostics

COMPUTER ENGINE CONTROLS

COMPUTER ENGINE CONTROLS

The Introduction of Electronic Engine Controls

As a result of increased air pollution (smog) in large
cities, such as Los Angeles, the California Air Resources
Board (CARB) and the Environmental Protection Agency
(EPA) set new regulations and air pollution standards to
deal with the problem. To further complicate matters, the
energy crisis of the early 1970s caused a sharp increase in
fuel prices over a short period. As a result, vehicle manufac­turers were not only required to comply with the new emis­sions standards, they also had to make their vehicles more fuel­efficient. Most vehicles were required to meet a miles-per-gallon
(MPG) standard set by the U.S. Federal Government.

Precise fuel delivery and spark timing are needed to reduce vehicle
emissions.Mechanical engine controls in use at the time (such as igni­tion points, mechanical spark advance and the carburetor) responded
too slowly to driving conditions to properly control fuel delivery and
spark timing. This made it difficult for vehicle manufacturers to meet
the new standards.

A new Engine Control System had to be designed and integrated with
the engine controls to meet the stricter standards.The new system had
to:

■ Respond instantly to supply the proper mixture of air and fuel for

any driving condition (idle, cruising, low-speed driving, high-speed
driving, etc.).

■ Calculate instantly the best time to “ignite” the air/fuel mixture for

maximum engine efficiency.

■ Perform both these tasks without affecting vehicle performance or

fuel economy.

Vehicle Computer Control Systems can perform millions of calcula­tions each second.This makes them an ideal substitute for the slower
mechanical engine controls. By switching from mechanical to elec­tronic engine controls, vehicle manufacturers are able to control fuel
delivery and spark timing more precisely. Some newer Computer
Control Systems also provide control over other vehicle functions,
such as transmission, brakes, charging, body, and suspension sys­tems.

Electronic Computer Control Systems make it possible

for vehicle manufacturers to comply with the tougher emis-

sions and fuel efficiency standards mandated by

State and Federal Governments.

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Onboard Diagnostics

COMPUTER ENGINE CONTROLS

The Basic Engine Computer Control System

The on-board computer is the heart of the Computer
Control System.The computer contains several programs
with preset reference values for air/fuel ratio, spark or igni­tion timing, injector pulse width, engine speed, etc.
Separate values are provided for various driving conditions,
such as idle, low speed driving, high-speed driving, low load,
or high load. The preset reference values represent the ideal
air/fuel mixture, spark timing, transmission gear selection,
etc., for any driving condition.These values are programmed
by the vehicle manufacturer, and are specific to each vehicle model.

Most on-board computers are located inside the vehicle behind the
dashboard, under the passenger’s or driver’s seat, or behind the right
kick panel. However, some manufacturers may still position it in the
engine compartment.

Vehicle sensors, switches, and actuators are located throughout the
engine, and are connected by electrical wiring to the on-board
computer. These devices include oxygen sensors, coolant tempera­ture sensors, throttle position sensors, fuel injectors, etc.Sensors and
switches are input devices.They provide signals representing current
engine operating conditions to the computer. Actuators are output
devices. They perform actions in response to commands received
from the computer.

The on-board computer receives information inputs from sensors and
switches located throughout the engine.These devices monitor critical
engine conditions such as coolant temperature, engine speed, engine
load, throttle position, air/fuel ratio etc.

The Computer Control System consists of an on-board
computer and several related control devices (sensors,

switches, and actuators).

OUTPUT DEVICES

Fuel Injectors
Idle Air Control
EGR Valve
Ignition Module

INPUT DEVICES

Coolant Temperature Sensor
Throttle Position Sensor
Fuel Injectors

On-Board
Computer

TYPICAL COMPUTER

CONTROL SYSTEM

INPUT DEVICES

Oxygen Sensors

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Onboard Diagnostics

COMPUTER ENGINE CONTROLS

The computer compares the values received from these sensors with
its preset reference values, and makes corrective actions as needed
so that the sensor values always match the preset ref erence values for
the current driving condition. The computer makes adjustments by
commanding other devices such as the fuel injectors, idle air control,
EGR valve or Ignition Module to perfor m these actions.

Vehicle operating conditions are constantly changing. The computer
continuously makes adjustments or corrections (especially to the
air/fuel mixture and spark timing) to keep all the engine systems oper­ating within the preset reference values.

On-Board Diagnostics - First Generation (OBD 1)

Beginning in 1988, California’s Air Resources Board

(CARB), and later the Environmental Protection Agency
(EPA) required vehicle manufacturers to include a self-
diagnostic program in their on-board computers.The pro-

gram would be capable of identifying emissions-related f aults

in a system. The first generation of Onboard Diagnostics

came to be known as OBD 1.

OBD 1 is a set of self-testing and diagnostic instructions pro­grammed into the vehicle’s on-board computer. The programs are
specifically designed to detect failures in the sensors, actuators,
switches and wiring of the various vehicle emissions-related systems.
If the computer detects a failure in any of these components or sys­tems, it lights an indicator on the dashboard to alert the driver.The indi­cator lights only when an emissions-related problem is detected.

The computer also assigns a numeric code for each specific problem
that it detects, and stores these codes in its memory for later retrieval.
These codes can be retrieved from the computer’s memory with the
use of a “Code Reader” or a “Scan Tool.”

With the exception of some 1994 and 1995 vehicles,

most vehicles from 1982 to 1995 are equipped with

some type of first generation On-Board Diagnostics.

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Onboard Diagnostics

COMPUTER ENGINE CONTROLS

On-Board Diagnostics - Second Generation (OBD 2)

In addition to performing all the func­tions of the OBD 1 System, the OBD 2
System has been enhanced with new
Diagnostic Programs.These programs
closely monitor the functions of vari­ous emissions-related components
and systems (as well as other sys­tems) and make this information readily available (with
the proper equipment) to the technician for evaluation.

The California Air Resources Board (CARB) conducted
studies on OBD 1 equipped vehicles. The information that
was gathered from these studies showed the following:

■ A large number of vehicles had deteriorating or degraded

emissions-related components. These components were
causing an increase in emissions.

■ Because OBD 1 systems only detect failed components, the

degraded components were not setting codes.

■ Some emissions problems related to degraded components only

occur when the vehicle is being driven under a load.The emission
checks being conducted at the time were not performed under sim­ulated driving conditions. As a result, a significant number of vehi­cles with degraded components were passing Emissions Tests.

■ Codes, code definitions, diagnostic connectors, communication

protocols and emissions terminology were different for each manu­facturer. This caused confusion for the technicians working on dif­ferent make and model vehicles.

To address the problems made evident by this study, CARB and the EPA
passed new laws and standardization requirements.These laws required
that vehicle manufacturers to equip their ne w v ehicles with de vices capa­ble of meeting all of the new emissions standards and regulations.It was
also decided that an enhanced on-board diagnostic system, capable of
addressing all of these problems, was needed.This new system is known
as “On-Board Diagnostics Generation Two (OBD 2).” The primary
objective of the OBD 2 system is to comply with the latest regulations and
emissions standards established by CARB and the EPA.

The Main Objectives of the OBD 2 System are:

■ To detect degraded and/or failed emissions-related components or

systems that could cause tailpipe emissions to exceed by 1.5 times
the Federal Test Procedure (FTP) standard.

■ To expand emissions-related system monitoring.This includes a set

of computer run diagnostics called Monitors.Monitors perform diag­nostics and testing to verify that all emissions-related components
and/or systems are operating correctly and within the manufactur­er’s specifications.

The OBD 2 System is

an enhancement of the

OBD 1 System.

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Onboard Diagnostics

COMPUTER ENGINE CONTROLS

■ To use a standardized Diagnostic Link Connector (DLC) in all vehi-

cles. (Before OBD 2, DLCs were of different shapes and sizes.)

■ To standardize the code numbers, code definitions and language

used to describe faults. (Before OBD 2, each vehicle manufacturer
used their own code numbers, code definitions and language to
describe the same faults.)

■ To expand the operation of the Malfunction Indicator Lamp (MIL).

■ To standardize communication procedures and protocols between

the diagnostic equipment (Scan Tools, Code Readers, etc.) and the
vehicle’s on-board computer.

OBD 2 Terminology

The following terms and their definitions are related to OBD 2 systems.
Read and reference this list as needed to aid in the understanding of
OBD 2 systems.

■ Powertrain Control Module (PCM) - The PCM is the OBD 2

accepted term for the vehicle’s “on-board computer.” In addition to
controlling the engine management and emissions systems, the
PCM also participates in controlling the powertrain (transmission)
operation. Most PCMs also have the ability to communicate with
other computers on the vehicle (ABS, ride control, body, etc.).

■ Monitor - Monitors are “diagnostic routines” programmed into the

PCM.The PCM utilizes these programs to run diagnostic tests, and
to monitor operation of the vehicle’s emissions-related components
or systems to ensure they are operating correctly and within the
vehicle’s manufacturer specifications. Currently, up to eleven
Monitors are used in OBD 2 systems. Additional Monitors will be
added as the OBD 2 system is further developed.

Not all vehicles support all eleven Monitors.

■ Enabling Criteria - Each Monitor is designed to test and monitor

the operation of a specific part of the vehicle’s emissions system
(EGR system, oxygen sensor, catalytic converter, etc.). A specific
set of “conditions” or “driving procedures” must be met before the
computer can command a Monitor to run tests on its related sys­tem. These “conditions” are known as “Enabling Criteria.” The
requirements and procedures vary for each Monitor.Some Monitors
only require the ignition key to be turned “On” for them to run and
complete their diagnostic testing. Others may require a set of com­plex procedures, such as, starting the vehicle when cold, bringing it
to operating temperature, and driving the vehicle under specific
conditions before the Monitor can run and complete its diagnostic
testing.

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Onboard Diagnostics

COMPUTER ENGINE CONTROLS

■ Monitor Has/Has Not Run - The terms “Monitor has run” or

“Monitor has not run” are used throughout this manual. “Monitor
has run,” means the PCM has commanded a particular Monitor to
perform the required diagnostic testing on a system to ensure the
system is operating correctly (within factory specifications). The
term “Monitor has not run” means the PCM has not yet com-
manded a particular Monitor to perform diagnostic testing on its
associated part of the emissions system.

■ Trip - A Trip for a particular Monitor requires that the vehicle is being

driven in such a way that all the required “Enabling Criteria” for the
Monitor to run and complete its diagnostic testing are met.The “Trip
Drive Cycle” for a particular Monitor begins when the ignition key is
turned “On.” It is successfully completed when all the “Enabling
Criteria” for the Monitor to run and complete its diagnostic testing
are met by the time the ignition key is turned “Off.” Since each of
the eleven monitors is designed to run diagnostics and testing on a
different part of the engine or emissions system, the “Trip Drive
Cycle” needed for each individual Monitor to run and complete
varies.

■ OBD 2 Drive Cycle - An OBD 2 Drive Cycle is an extended set of

driving procedures that takes into consideration the various types of
driving conditions encountered in real life. These conditions may
include starting the vehicle when it is cold, driving the vehicle at a
steady speed (cruising), accelerating, etc. An OBD 2 Dr ive Cycle
begins when the ignition key is turned “On” (when cold) and ends
when the vehicle has been driven in such a way as to have all the
“Enabling Criteria” met for all its applicable Monitors. Only those
trips that provide the Enabling Criteria for all Monitors applicable to
the vehicle to run and complete their individual diagnostic tests
qualify as an OBD 2 Drive Cycle. OBD 2 Drive Cycle requirements
vary from one model of vehicle to another.Vehicle manufacturers
set these procedures. Consult your vehicle’s service manual for
OBD 2 Drive Cycle procedures.

Do not confuse a “Trip” Drive Cycle with an OBD 2 Drive
Cycle.A “T rip”Drive Cycle provides the “Enabling Criteria” for
one specific Monitor to r un and complete its diagnostic test­ing. An OBD 2 Drive Cycle must meet the “Enabling Criteria”
for all Monitors on a particular vehicle to run and complete
their diagnostic testing.

■ Warm-up Cycle - Vehicle operation after an engine off period

where engine temperature rises at least 40°F (22°C) from its tem­perature before starting, and reaches at least 160°F (70°C). The
PCM uses warm-up cycles as a counter to automatically erase a
specific code and related data from its memory. When no faults
related to the original problem are detected within a specified num­ber of warm-up cycles, the code is erased automatically.

20 CAN OBD2

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Onboard Diagnostics

DIAGNOSTIC TROUBLE CODES (DTCs)

DIAGNOSTIC TROUBLE CODES (DTCs)

Diagnostic Trouble Codes (DTCs) are
meant to guide you to the proper serv­ice procedure in the vehicle’s service
manual. DO NOT replace parts based
only on DTCs without first consulting
the vehicle’s service manual for prop­er testing procedures for that particular
system, circuit or component.

DTCs are alphanumeric codes that are used to identify a
problem that is present in any of the systems that are mon­itored by the on-board computer (PCM). Each trouble code
has an assigned message that identifies the circuit, compo­nent or system area where the problem was found.

OBD 2 diagnostic trouble codes are made up of five charac­ters:

■ The 1st character is a letter. It identifies the “main system” where

the fault occurred (Body, Chassis, Power train, or Network).

■ The 2nd character is a n umeric digit.It identifies the “type” of code

(Generic or Manufacturer-Specific).

Generic DTCs are codes that are used by all vehicle manu­facturers. The standards for generic DTCs, as well as their
definitions, are set by the Society of Automotive Engineers
(SAE).

Manufacturer-Specific DTCs are codes that are controlled
by the vehicle manufacturers. The Federal Government does
not require vehicle manufacturers to go beyond the stan­dardized generic DTCs in order to comply with the new
OBD2 emissions standards.However, man ufacturers are free
to expand beyond the standardized codes to make their sys­tems easier to diagnose.

■ The 3rd character is a numeric digit. It identifies the specific sys-

tem or sub-system where the problem is located.

■ The 4th and 5th characters are numeric digits. They identify the

section of the system that is malfunctioning.

Diagnostic T rouble

Codes (DTCs) are

codes that identify a

specific problem area.

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Onboard Diagnostics

DIAGNOSTIC TROUBLE CODES (DTCs)

DTCs and MIL Status

When the vehicle’s on-board computer detects
a failure in an emissions-related component
or system, the computer’s internal diagnostic
program assigns a diagnostic trouble code
(DTC) that points to the system (and sub­system) where the fault was found.The diag­nostic program saves the code in the com­puter’s memory. It records a “Freeze Frame” of
conditions present when the fault was found, and lights the Malfunction
Indicator Lamp (MIL). Some faults require detection for two trips in a
row before the MIL is turned on.

The “Malfunction Indicator Lamp” (MIL) is the accepted term
used to describe the lamp on the dashboard that lights to
warn the driver that an emissions-related fault has been
found. Some manufacturers may still call this lamp a “Check
Engine” or “Service Engine Soon” light.

P0201 - Injector Circuit Malfunction, Cylinder 1

OBD 2 DTC EXAMPLE

B

-

Body

C

-

Chassis

P

-

Powertrain

U

-

Network

-

Generic

0

-

Manufacturer Specific

1

-

Generic

2

-

Includes both Generic and Manufacturer

3

Specific Codes

Identifies the system where the
problem is located:

1

-

Fuel and Air Metering

2

-

Fuel and Air Metering (injector circuit
malfunction only)

3

-

Ignition System or Misfire

4

-

Auxiliary Emission Control System

5

-

Vehicle Speed Control and Idle Control
System

6

-

Computer Output Circuits

7

-

Transmission

8

-

Transmission

Identifies what section of the system
is malfunctioning

P 0 2 0 1

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Onboard Diagnostics

DIAGNOSTIC TROUBLE CODES (DTCs)

There are two types of DTCs used for emissions-related faults:Type
“A” and Type “B.” Type “A” codes are “One-Trip” codes;Type “B” DTCs
are usually Two-Trip DTCs.

When a Type “A” DTC is found on the First Trip, the following events
take place:

■ The computer commands the MIL “On” when the failure is first

found.

■ If the failure causes a severe misfire that may cause damage to the

catalytic converter, the MIL “flashes” once per second. The MIL
continues to flash as long as the condition exists. If the condition
that caused the MIL to flash is no longer present, the MIL will light
“steady” On.

■ A DTC is saved in the computer’s memory for later retrieval.

■ A “Freeze Frame” of the conditions present in the engine or emis-

sions system when the MIL was ordered “On” is saved in the com­puter’s memory for later retrieval. This information shows fuel sys­tem status (closed loop or open loop), engine load, coolant tem­perature, fuel trim value, MAP vacuum, engine RPM and DTC pri­ority.

When a Type “B” DTC is found on the First Trip, the following events
take place:

■ The computer sets a Pending DTC, but the MIL is not ordered “On.”

“Freeze Frame” data may or may not be saved at this time depend­ing on manufacturer. The Pending DTC is saved in the computer’s
memory for later retrieval.

■ If the failure is found on the second consecutive trip, the MIL is

ordered “On.”“Freeze Frame”data is sa ved in the computer’s mem­ory.

■ If the failure is not found on the second Trip, the Pending DTC is

erased from the computer’s memory.

The MIL will stay lit for both Type “A” and Type “B” codes until one of
the following conditions occurs:

■ If the conditions that caused the MIL to light are no longer present

for the next three trips in a row, the computer automatically turns the
MIL “Off” if no other emissions-related faults are present. However,
the DTCs remain in the computer’s memory as a history code for 40
warm-up cycles (80 warm-up cycles for fuel and misfire faults).The
DTCs are automatically erased if the fault that caused them to be
set is not detected again during that period.

■ Misfire and fuel system faults require three trips with “similar condi-

tions” before the MIL is turned “Off.” These are trips where the
engine load, RPM and temperature are similar to the conditions
present when the fault was first found.

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Onboard Diagnostics

OBD 2 MONITORS

After the MIL has been turned off, DTCs, Freez e Frame data,
and manufacturer-specific enhanced data stay in the com­puter’s memory. Most of the enhanced data can only be
retrieved with special equipment such as a Scan Tool.

■ Erasing the DTCs from the computer’s memory can also turn off the

MIL. See ERASING DIAGNOSTIC TROUBLE CODES (DTCs) on
page 41, before erasing codes from the computer’s memory. If a
Code Reader or Scan Tool is used to erase the codes, Freeze
Frame data as well as other manufacturer-specific enhanced data
will also be erased.

OBD 2 MONITORS

To ensure the correct operation of the various emissions-related com­ponents and systems, a diagnostic program was developed and
installed in the vehicle’s on-board computer. The program has several
procedures and diagnostic strategies. Each procedure or diagnostic
strategy is made to monitor the operation of, and run diagnostic tests
on, a specific emissions-related component or system. These tests
ensure the system is running correctly and is within the manufacturer’s
specifications. On OBD 2 systems, these procedures and diagnostic
strategies are called “Monitors.”

Currently, a maximum of eleven Monitors are used in OBD 2 systems.
Additional monitors may be added as a result of Government regula­tions as the OBD 2 system grows and matures. Not all vehicles sup­port all eleven Monitors.

Monitor operation is either “Continuous” or “Non-Continuous,”
depending on the specific monitor.

Continuous Monitors

Three of these Monitors are designed to constantly monitor their asso­ciated components and/or systems for proper operation. Continuous
Monitors run constantly when the engine is running. The Continuous
Monitors are:

Comprehensive Component Monitor (CCM)
Misfire Monitor
Fuel System Monitor

Non-Continuous Monitors

The other eight Monitors are “non-continuous”Monitors.“Non-continu­ous” Monitors perform and complete their testing once per trip. The
“non-continuous” Monitors are:

24 CAN OBD2

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Onboard Diagnostics

OBD 2 MONITORS

Oxygen Sensor Monitor
Oxygen Sensor Heater Monitor
Catalyst Monitor
Heated Catalyst Monitor
EGR System Monitor
EVAP System Monitor
Secondary Air System Monitor
Air Conditioning (A/C) Monitor

The following provides a brief explanation of the function of each
Monitor:

Comprehensive Component Monitor (CCM) - This Monitor

continuously checks all inputs and outputs from sensors, actu­ators, switches and other devices that provide a signal to the comput­er.The Monitor checks for shorts, opens, out of range value, function­ality and “rationality.”

Rationality: Each input signal is compared against all other
inputs and against information in the computer’s memory to
see if it makes sense under the current operating conditions.
Example: The signal from the throttle position sensor indi­cates the vehicle is in a wide-open throttle condition, but the
vehicle is really at idle, and the idle condition is confirmed by
the signals from all other sensors. Based on the input data,
the computer determines that the signal from the throttle
position sensor is not rational (does not make sense when
compared to the other inputs). In this case, the signal would
fail the rationality test.

The CCM may be either a “One-Trip” or a “Two-Trip” Monitor, depend­ing on the component.

Fuel System Monitor - This Monitor uses a Fuel System Cor-

rection program, called Fuel Trim, inside the on-board comput­er. Fuel Trim is a set of positive and negative values that represent
adding or subtracting fuel from the engine.This program is used to cor­rect for a lean (too much air/not enough fuel) or rich (too much fuel/not
enough air) air-fuel mixture. The program is designed to add or sub­tract fuel, as needed, up to a certain percent. If the correction needed
is too large and exceeds the time and percent allowed by the prog r am,
a fault is indicated by the computer.

The Fuel System Monitor may be a “One-Trip” or “Two-Trip” Monitor,
depending on the severity of the problem.

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Onboard Diagnostics

OBD 2 MONITORS

Misfire Monitor - This Monitor continuously checks for engine

misfires. A misfire occurs when the air-fuel mixture in the cylin­der does not ignite. The misfire Monitor uses changes in crankshaft
speed to sense an engine misfire. When a cylinder misfires, it no
longer contributes to the speed of the engine, and engine speed
decreases each time the affected cylinder(s) misfire. The misfire
Monitor is designed to sense engine speed fluctuations and determine
from which cylinder(s) the misfire is coming, as well as how bad the
misfire is.There are three types of engine misfires, Types 1, 2, and 3.

- Type 1 and Type 3 misfires are two-tr ip monitor faults. If a fault is
sensed on the first trip, the computer temporarily saves the fault in
its memory as a Pending Code. The MIL is not commanded on at
this time. If the fault is found again on the second trip, under similar
conditions of engine speed, load and temperature, the computer
commands the MIL “On,”and the code is sa ved in its long term mem­ory.

- Type 2 misfires are the most severe type of misfire.When a Type 2
misfire is sensed on the first trip, the computer commands the MIL
to light when the misfire is sensed. If the computer determines that
a Type 2 misfire is severe , and may cause catalytic conver ter dam­age, it commands the MIL to “flash”once per second as soon as the
misfire is sensed. When the misfire is no longer present, the MIL
reverts to steady “On” condition.

Catalyst Monitor - The catalytic converter is a device that is

installed downstream of the exhaust manifold.It helps to oxidize
(burn) the unburned fuel (hydrocarbons) and partially burned fuel (car­bon monoxide) left over from the combustion process. To accomplish
this, heat and catalyst materials inside the converter react with the
exhaust gases to burn the remaining fuel. Some materials inside the
catalytic converter also have the ability to store oxygen, and release it
as needed to oxidize hydrocarbons and carbon monoxide. In the
process, it reduces vehicle emissions by converting the polluting
gases into carbon dioxide and water.

The computer checks the efficiency of the catalytic converter by mon­itoring the oxygen sensors used by the system.One sensor is located
before (upstream of) the converter; the other is located after (down­stream of) the converter. If the catalytic converter loses its ability to
store oxygen, the downstream sensor signal voltage becomes almost
the same as the upstream sensor signal. In this case, the monitor fails
the test.

The Catalyst Monitor is a “Two-Trip” Monitor. If a fault is found on the
first trip, the computer temporarily saves the fault in its memory as a
Pending Code. The computer does not command the MIL on at this
time.If the fault is sensed again on the second trip, the computer com­mands the MIL “On” and saves the code in its long-term memory.

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Onboard Diagnostics

OBD 2 MONITORS

Heated Catalyst Monitor - Operation of the “heated” catalytic

converter is similar to the catalytic converter. The main differ­ence is that a heater is added to bring the catalytic converter to its
operating temperature more quickly. This helps reduce emissions by
reducing the converter’s down time when the engine is cold. The
Heated Catalyst Monitor performs the same diagnostic tests as the
catalyst Monitor, and also tests the catalytic converter’s heater for
proper operation.This Monitor is also a “Two-Trip”Monitor.

Exhaust Gas Recirculation (EGR) Monitor - The Exhaust

Gas Recirculation (EGR) system helps reduce the formation of
Oxides of Nitrogen during combustion. Temperatures above 2500°F
cause nitrogen and oxygen to combine and form Oxides of Nitrogen in
the combustion chamber. To reduce the formation of Oxides of
Nitrogen, combustion temperatures must be kept below 2500°F. The
EGR system recirculates small amounts of exhaust gas back into the
intake manifold, where it is mixed with the incoming air/fuel mixture.
This reduces combustion temperatures by up to 500°F. The computer
determines when, for how long, and how much exhaust gas is recircu­lated back to the intake manifold.The EGR Monitor performs EGR sys­tem function tests at preset times during vehicle operation.

The EGR Monitor is a “Two-Trip” Monitor. If a fault is found on the first
trip, the computer temporarily saves the fault in its memory as a
Pending Code. The computer does not command the MIL on at this
time.If the fault is sensed again on the second trip, the computer com­mands the MIL “On,” and saves the code in its long-term memory.

Evaporative System (EVAP) Monitor - OBD 2 vehicles are

equipped with a fuel Evaporative system (EVAP) that helps pre­vent fuel vapors from evaporating into the air.The EVAP system car­ries fumes from the fuel tank to the engine where they are burned dur­ing combustion.The EVAP system may consist of a charcoal canister,
fuel tank cap, purge solenoid, vent solenoid, flow monitor, leak detec­tor and connecting tubes, lines and hoses.

Fumes are carried from the fuel tank to the charcoal canister by hoses
or tubes.The fumes are stored in the charcoal canister.The computer
controls the flow of fuel vapors from the charcoal canister to the engine
via a purge solenoid. The computer energizes or de-energizes the
purge solenoid (depending on solenoid design). The purge solenoid
opens a valve to allow engine v acuum to dr a w the fuel vapors from the
canister into the engine where the vapors are burned. The EVAP
Monitor checks for proper fuel vapor flow to the engine, and pressur­izes the system to test for leaks.The computer runs this Monitor once
per trip.

The EVAP Monitor is a “Two-Trip” Monitor.If a fault is found on the first
trip, the computer temporarily saves the fault in its memory as a
Pending Code. The computer does not command the MIL on at this
time. If the fault is sensed again on the second trip, the PCM com­mands the MIL “On,” and saves the code in its long-term memory.

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Onboard Diagnostics

OBD 2 MONITORS

Air Conditioning (A/C) Monitor - The A/C Monitor senses

leaks in air conditioning systems that utilize R-12 refrigerant.
Vehicle manufacturers have been given two options:

1. Use R-12 refrigerant in their A/C systems, and integrate an A/C

Monitor in the OBD 2 systems of these vehicles to detect for refrig­erant leaks; or

2. Use R-134 refrigerant instead of R12. The A/C Monitor is not

required on these vehicles.

To date, all vehicle manufacturers ha v e opted to use R-134 in their A/C
systems. As a result, this Monitor has not yet been implemented.

Oxygen Sensor Heater Monitor - The Oxygen Sensor Heater

Monitor tests the operation of the oxygen sensor’ s heater .There
are two modes of operation on a computer-controlled vehicle: “open­loop” and “closed-loop.” The vehicle operates in open-loop when the
engine is cold, before it reaches normal operating temperature. The
vehicle also goes to open-loop mode at other times, such as heavy
load and full throttle conditions. When the vehicle is running in open­loop, the oxygen sensor signal is ignored by the computer for air/fuel
mixture corrections. Engine efficiency during open-loop operation is
very low, and results in the production of more vehicle emissions.

Closed-loop operation is the best condition for both vehicle emissions
and vehicle operation. When the vehicle is operating in closed-loop,
the computer uses the oxygen sensor signal for air/fuel mixture cor­rections.

In order for the computer to enter closed-loop operation, the oxygen
sensor must reach a temperature of at least 600°F.The o xygen sensor
heater helps the oxygen sensor reach and maintain its minimum oper­ating temperature (600°F) more quickly, to bring the vehicle into
closed-loop operation as soon as possible.

The Oxygen Sensor Heater Monitor is a “Two-Trip”Monitor. If a fault is
found on the first trip, the computer temporarily saves the fault in its
memory as a Pending Code. The computer does not command the
MIL on at this time. If the fault is sensed again on the second trip, the
computer commands the MIL “On,” and sav es the code in its long-term
memory.

Oxygen Sensor Monitor - The Oxygen Sensor monitors how

much oxygen is in the vehicle’s exhaust. It generates a varying
voltage of up to one volt, based on how much oxygen is in the exhaust
gas, and sends the signal to the computer.The computer uses this sig­nal to make corrections to the air/fuel mixture. If the exhaust gas has
a large amount of oxygen (a lean air/fuel mixture), the oxygen sensor
generates a “low”voltage signal. If the exhaust gas has very little oxy­gen (a rich mixture condition), the oxygen sensor generates a “high”
voltage signal. A 450mV signal indicates the most efficient, and least
polluting, air/fuel ratio of 14.7 parts of air to one part of fuel.

28 CAN OBD2

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Onboard Diagnostics

OBD 2 MONITORS

The oxygen sensor must reach a temperature of at least 600-650°F,
and the engine must reach normal operating temperature, for the
computer to enter into closed-loop operation.The oxygen sensor only
functions when the computer is in closed-loop. A properly operating
oxygen sensor reacts quickly to any change in oxygen content in the
exhaust stream.A faulty oxygen sensor reacts slowly, or its voltage sig­nal is weak or missing.

The oxygen sensor is a “Two-T rip”monitor.If a f ault is found on the first
trip, the computer temporarily saves the fault in its memory as a
Pending Code. The computer does not command the MIL on at this
time.If the fault is sensed again on the second trip, the computer com­mands the MIL “On,” and saves the code in its long-term memory.

Secondary Air System Monitor - When a cold engine is first

started, it runs in open-loop mode. During open-loop operation,
the engine usually runs rich. A vehicle running rich wastes fuel and
creates increased emissions, such as carbon monoxide and some
hydrocarbons. A Secondary Air System injects air into the exhaust
stream to aid catalytic converter operation:

1. It supplies the catalytic converter with the oxygen it needs to oxidize

the carbon monoxide and hydrocarbons left over from the combus­tion process during engine warm-up.

2. The extra oxygen injected into the exhaust stream also helps the

catalytic converter reach operating temperature more quickly dur­ing warm-up periods. The catalytic converter must heat to operat­ing temperature to work properly.

The Secondary Air System Monitor checks for component integrity and
system operation, and tests for faults in the system.The computer runs
this Monitor once per trip.

The Secondary Air System Monitor is a “Two-Trip” monitor. If a fault is
found on the first trip, the computer temporarily saves this fault in its
memory as a Pending Code. The computer does not command the
MIL on at this time. If the fault is sensed again on the second trip, the
computer commands the MIL “On,” and sav es the code in its long-term
memory.

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Onboard Diagnostics

OBD 2 MONITORS

OBD 2 Reference Table

The table below lists current OBD 2 Monitors, and indicates the fol­lowing for each Monitor:

A. Monitor Type (how often does the Monitor run; Continuous or Once

per trip)

B. Number of trips needed, with a fault present, to set a pending DTC
C. Number of consecutive trips needed, with a fault present, to com-

mand the MIL “On” and store a DTC

D. Number of trips needed, with no faults present, to erase a Pending

DTC

E. Number and type of trips or drive cycles needed, with no faults

present, to turn off the MIL

F. Number of warm-up periods needed to erase the DTC from the

computer’s memory after the MIL is turned off

Name of

Monitor A B C D E F

Comprehensive

Continuous 121340

Component Monitor
Misfire Monitor

Continuous 1 2 1

3 - similar

80

(Type 1 and 3) conditions
Misfire Monitor

Continuous 1

3 - similar

80

(Type 2) conditions
Fuel System

Continuous 1 1 or 2 1

3 - similar

80

Monitor conditions
Catalytic Converter Once per

1 2 1 3 trips 40

Monitor trip
Oxygen Sensor Once per

1 2 1 3 trips 40

Monitor trip
Oxygen Sensor Once per

1 2 1 3 trips 40

Heater Monitor trip
Exhaust Gas

Once per

1 2 1 3 trips 40

Recirculation (EGR)

trip

Monitor
Evaporative

Once per

1 2 1 3 trips 40

Emissions Controls

trip

Monitor
Secondary Air

Once per

1 2 1 3 trips 40

System (AIR)

trip

Monitor

30 CAN OBD2

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Preparation for Testing

PRELIMINARY VEHICLE DIAGNOSIS WORKSHEET

PRELIMINARY VEHICLE DIAGNOSIS WORKSHEET

The purpose of this form is to help you gather preliminary information on
your vehicle before you retrieve codes.By having a complete account of
your vehicle's current problem(s), you will be able to systematically pin­point the problem(s) by comparing your answers to the fault codes you
retrieve. You can also provide this information to your mechanic to assist
in diagnosis and help avoid costly and unnecessary repairs. It is impor­tant for you to complete this f orm to help you and/or y our mechanic have
a clear understanding of your vehicle's problems. An electronic version
of this Preliminary Vehicle Diagnosis Worksheet is available online at
www

.canOBD2.com.You can complete the form online and print a copy

to take to your mechanic.

NAME:
DATE:
VIN*:
YEAR:
MAKE:
MODEL:
ENGINE SIZE:
VEHICLE MILEAGE:

*VIN: Vehicle Identification Number, found at the base of the windshield
on a metallic plate, or at the driver door latch area (consult your vehicle
owner's manual for location).

TRANSMISSION:

❑

Automatic

❑ Manual

Please check all applicable items in each category.

DESCRIBE THE PROBLEM:

CAN OBD2 31

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Preparation for Testing

PRELIMINARY VEHICLE DIAGNOSIS WORKSHEET

WHEN DID YOU FIRST NOTICE THE PROBLEM:

❑ Just Started
❑ Star ted Last Week
❑ Star ted Last Month
❑ Other:

LIST ANY REPAIRS DONE IN THE PAST SIX MONTHS:

PROBLEMS STARTING

ENGINE QUITS OR STALLS

IDLING CONDITIONS

RUNNING CONDITIONS

❑ No symptoms
❑ Will not crank

❑ Cranks, but will not start
❑ Star ts, but takes a long time

❑ No symptoms
❑ Right after star ting
❑ When shifting into gear
❑ During steady-speed dr iving

❑ Right after vehicle comes to a stop
❑ While idling
❑ During acceleration
❑ When parking

❑ No symptoms
❑ Is too slow at all times
❑ Is too fast

❑ Is sometimes too fast or too slow
❑ Is rough or uneven
❑ Fluctuates up and down

❑ No symptoms
❑ Runs rough
❑ Lacks power
❑ Bucks and jerks
❑ Poor fuel economy
❑ Hesitates or stumbles on

accelerations

❑ Backfires
❑ Misfires or cuts out
❑ Engine knocks, pings or rattles
❑ Surges
❑ Dieseling or run-on

32 CAN OBD2

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Preparation for Testing

PRELIMINARY VEHICLE DIAGNOSIS WORKSHEET

AUTOMATIC TRANSMISSION PROBLEMS (if applicable)

PROBLEM OCCURS

❑ Morning ❑ Afternoon ❑ Anytime

ENGINE TEMPERATURE WHEN PROBLEM OCCURS

❑ Cold ❑ Warm ❑ Hot

DRIVING CONDITIONS WHEN PROBLEM OCCURS

DRIVING HABITS

GASOLINE USED

WEATHER CONDITIONS WHEN PROBLEM OCCURS

CHECK ENGINE LIGHT / DASH WARNING LIGHT

❑

Sometimes ON ❑ Always ON ❑ Never ON

PECULIAR SMELLS

STRANGE NOISES

❑ Shor t - less than 2 miles
❑ 2 - 10 miles
❑ Long - more than 10 miles
❑ Stop and go
❑ While turning
❑ While braking
❑ At gear engagement
❑ With A/C operating

❑ With headlights on
❑ During acceleration
❑ Mostly driving downhill
❑ Mostly driving uphill
❑ Mostly driving level
❑ Mostly driving cur vy roads
❑ Mostly driving rough roads

❑ Mostly city driving
❑ Highway
❑ Park vehicle inside
❑ Park vehicle outside

❑ Drive less than 10 miles per day
❑ Drive 10 to 50 miles per day
❑ Drive more than 50 miles per day

❑ 87 Octane
❑ 89 Octane

❑ 91 Octane
❑ More than 91 Octane

❑ 32 - 55° F (0 - 13° C)
❑ Below freezing (32° F / 0° C)

❑ Above 55° F (13° C)

❑ "Hot"
❑ Sulfur ("rotten egg")
❑ Burning r ubber

❑ Gasoline
❑ Burning oil
❑ Electrical

❑ Rattle
❑ Knock

❑ Squeak
❑ Other

❑ No symptoms
❑ Shifts too early or too late
❑ Changes gear incorrectly

❑ Vehicle does not move when in

gear

❑ Jerks or bucks

CAN OBD2 33

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Preparation for Testing

BEFORE YOU BEGIN

BEFORE Y OU BEGIN

The CAN OBD2 Code Reader
aids in monitoring electronic­and emissions-related faults in
your vehicle and retrieving
fault codes related to malfunc­tions in these systems.
Mechanical problems such as
low oil level or damaged
hoses, wiring or electrical connectors can cause poor engine perform­ance and may also cause a fault code to set.Fix any known mechan­ical problems before perfor ming any test. See your vehicle’s service
manual or a mechanic for more information.

Check the following areas before starting any test:

■ Check the engine oil, power steering fluid, transmission fluid (if

applicable), engine coolant and other fluids for proper le v els .Top off
low fluid levels if needed.

■ Mak e sure the air filter is clean and in good condition.Make sure all

air filter ducts are properly connected. Check the air filter ducts for
holes, rips or cracks.

■ Mak e sure all engine belts are in good condition.Check for cracked,

torn, brittle, loose or missing belts.

■ Make sure mechanical linkages to engine sensors (throttle,

gearshift position, transmission, etc.) are secure and properly con­nected. See your vehicle’s service manual for locations.

■ Check all rubber hoses (radiator) and steel hoses (vacuum/fuel) for

leaks, cracks, blockage or other damage. Make sure all hoses are
routed and connected properly.

■ Make sure all spark plugs are clean and in good condition. Check

for damaged, loose, disconnected or missing spark plug wires.

■ Make sure the batter y terminals are clean and tight. Check for cor-

rosion or broken connections. Check for proper battery and charg­ing system voltages.

■ Check all electrical wiring and harnesses for proper connection.

Make sure wire insulation is in good condition, and there are no
bare wires.

■ Make sure the engine is mechanically sound. If needed, perform a

compression check, engine vacuum check, timing chec k (if applica­ble), etc.

34 CAN OBD2

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Preparation for Testing

VEHICLE SERVICE MANUALS

VEHICLE SERVICE MANUALS

Always refer to the manufacturer’s service manual for your vehicle
before performing any test or repair procedures.Contact your local car
dealership, auto parts store or bookstore for availability of these man­uals.The following companies publish valuable repair manuals:

■ Haynes Publications

861 Lawrence Drive
Newbury Park, California 91320
Phone: [phone]

■ Mitchell International

14145 Danielson Street
Poway, California 92064
Phone: [phone]

■ Motor Publications

5600 Crooks Road, Suite 200
Troy, Michigan 48098
Phone: [phone]

FACTORY SOURCES

Ford, GM, Chrysler, Honda, Isuzu, Hyundai and Subaru Service
Manuals

■ Helm Inc.

14310 Hamilton Avenue
Highland Park, Michigan 48203
Phone: [phone]

CAN OBD2 35

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Using the Code Reader

CODE RETRIEVAL PROCEDURE

CODE RETRIEVAL PROCEDURE

Never replace a par t based only on the DTC definition.

Each DTC has a set of testing procedures, instructions
and flow charts that must be followed to confirm the loca­tion of the problem.This information is found in the vehicle's
service manual. Always refer to the vehicle's service manual
for detailed testing instructions.

Check your vehicle thoroughly before performing
any test. See Before You Begin on page 33 for
details.

ALWAYS observe safety precautions whenever working on a
vehicle. See Safety Precautions on page 3 for more infor-
mation.

1. Turn the ignition off.

2. Locate the vehicle's 16-pin Data Link

Connector (DLC). See page 5 for con­nector location.

Some DLCs have a plastic cover
that must be removed bef ore con­necting the Code Reader cable
connector.

If the Code Reader is ON, turn it
OFF by pressing the POWER/LINK

button BEFORE connecting

the Code Reader to the DLC.

3. Connect the Code Reader cable connector to the vehicle’s DLC.

The cable connector is keyed and will only fit one way.

■ If y ou ha ve problems connecting the cable connector to the DLC,

rotate the connector 180° and try again.

■ If you still have problems, check the DLC on the vehicle and on

the Code Reader.Refer to your vehicle’ s service manual to prop­erly check the vehicle’s DLC.

4. When the Code Reader’s cable connec-

tor is properly connected to the vehicle’s
DLC, the unit automatically turns ON,
and the LCD display shows instructions
for linking to the vehicle’s on-board
computer.

Retrieving and using Diagnostic Trouble Codes (DTCs) for

troubleshooting vehicle operation is only one part of an

overall diagnostic strategy.

36 CAN OBD2

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Using the Code Reader

CODE RETRIEVAL PROCEDURE

■ If the unit does not power on automatically when connected to

the vehicle’s DLC connector, it usually indicates there is no
power present at the vehicle’s DLC connector. Check your fuse
panel and replace any burned-out fuses.

■ If replacing the fuse(s) does not correct the prob lem, consult your

vehicle’s repair man ual to identify the proper computer (PCM) fuse/
circuit, and perform any necessary repairs before proceeding.

5. Turn the ignition on. DO NOT start the engine.

6. Press and release the Code Reader’s POWER/LINK button.

■ The Code Reader will automatically

start a check of the vehicle’s comput­er to determine which type of com­munication protocol it is using. When
the Code Reader identifies the com­puter’s communication protocol, a
communication link is established.
The protocol type used by the vehi­cle’s computer is shown on the LCD
display.

A PROTOCOL is a set of rules and procedures for regu­lating data transmission between computers, and between
testing equipment and computers. As of this wr iting, five
different types of protocols (ISO 9141, Keyword 2000,
J1850 PWM, J1850 VPW and CAN) are in use by vehicle
manufacturers. The Code Reader automatically identifies
the protocol type and establishes a communication link
with the vehicle’s computer.

7. After approximately 4~5 seconds, the Code Reader will retrieve

and display any Diagnostic Trouble Codes, Monitor Status and
Freeze Frame Data retrieved from the vehicle’s computer memory.

■ If the Code Reader fails to link to the

vehicle’s computer a “Linking Failed”
message shows on the Code
Reader’s LCD display.

- Verify the connection at the DLC:
and verify the ignition is ON.

- Turn the ignition OFF, wait 5 seconds, then turn back ON to
reset the computer.

- Ensure your vehicle is OBD2 compliant. See Vehicles
Covered on page 5 for vehicle compliance verification infor­mation.

CAN OBD2 37

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Using the Code Reader

CODE RETRIEVAL PROCEDURE

■ The Code Reader will automatically

re-link to the vehicle’s computer e v ery
15 seconds to refresh the data being
retrieved. When data is being re­freshed, the message “One moment
Auto – link in progress”is shown on the
LCD display. This action repeats as
long as the Code Reader is commu­nicating with the vehicle’s computer.

■ The Code Reader will display a code

only if codes are present in the vehi­cle’s computer memory. If no codes
are present, a “No DTC’ s are present­ly stored in the vehicle’s computer”is
displayed.

■ The Code Reader is capable of retrieving and storing up to 32

codes in memory, for immediate or later viewing.

8. To read the display:

Refer to Display Functions on page 25 for a description
of LCD display elements.

■ A visible icon indicates that the Code Reader is being pow-

ered through the vehicle’s DLC connector.

■ A visible icon indicates that the Code Reader is linked to

(communicating with) the vehicle’s computer.

■ The I/M Monitor Status icons indicate the type and number of

Monitors the vehicle supports, and provides indications of the
current status of the vehicle’s Monitors .A solid Monitor icon indi­cates the associated Monitor has run and completed its testing.
A blinking Monitor icon indicates the associated Monitor has
not run and completed its testing.

■ The upper right hand corner of the

display shows the number of the code
currently being displayed, the total
number of codes retrieved, the type
of code (G = Gener ic; E = Enhanced
or Manufacturer specific), and
whether or not the displayed code
commanded the MIL on. If the code
being displayed is a PENDING code, the PENDING icon is
shown.

■ The Diagnostic Trouble Code (DTC) and related code definition

are shown in the lower section of the LCD display.

38 CAN OBD2

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Using the Code Reader

CODE RETRIEVAL PROCEDURE

In the case of long code definitions, or when viewing
Freeze Frame data, a small arrow is shown in the
upper/lower right-hand corner of the code display area
to indicate the presence of additional information. Use
the

and

buttons, as necessary , to vie w the addi-

tional information.

9. Read and interpret Diagnostic Trouble Codes/system condition
using the LCD display and the green, yellow and red LEDs.

The green, yellow and red LEDs are used (with the LCD
display) as visual aids to make it easier to determine
engine system conditions.

■ Green LED – Indicates that all

engine systems are “OK” and operat­ing normally. All monitors supported
by the vehicle have run and per­formed their diagnostic testing, and
no trouble codes are present. A zero
will show on the Code Reader’s LCD
display, and all Monitor icons will be
solid.

■ Yellow LED – Indicates one of the following conditions:

A. A PENDING CODE IS PRESENT – If

the yellow LED is illuminated, it may
indicate a Pending code is present.
Check the Code Reader’s LCD dis­play for confirmation.A Pending code
is confirmed by the presence of a
numeric code and the word PEND­ING on the Code Reader’s LCD dis­play.

B. MONITOR NO T R UN STA TUS – If the

Code Reader’s LCD display shows a
zero (indicating there are no DTC’s
present in the vehicle’s computer
memory), but the yellow LED is illu­minated, it may be an indication that
some of the Monitors supported by
the vehicle have not y et run and com­pleted their diagnostic testing. Check
the Code Reader’s LCD display for confirmation. All Monitor
icons that are blinking have not yet run and completed their
diagnostic testing; all Monitor icons that are solid have run and
completed their diagnostic testing.

CAN OBD2 39

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Using the Code Reader

CODE RETRIEVAL PROCEDURE

■ Red LED – Indicates there is a prob-

lem with one or more of the vehicle’s
systems.The red LED is also used to
indicate that DTC(s) are present (dis­played on the Code Reader’s screen).
In this case, the Multifunction Indicator
(Check Engine) lamp on the vehicle’s
instrument panel will be illuminated.

On some vehicle models, the computer will store non­emission related DTCs.These DTCs will not command the
MIL on since they are not emission related. If the Code
Reader retrieves one of these types of codes, the MIL will
not be commanded on, and the Yellow LED on the Code
Reader will be illuminated.

■ DTC’s that start with “P0”, “P2” and some “P3” are considered

Generic (Universal).All Generic DTC definitions are the same on
all OBD2 equipped vehicles.The Code Reader automatically dis­plays the code definitions for Generic DTC’s.

■

DTC’s that start with “P1” and some
“P3” are Enhanced (Manufacturer spe­cific) codes and their code definitions
vary with each vehicle manufacturer.
When an Enhanced (Manufacturer
specific) DTC is retrieved, the LCD dis­play shows a list of vehicle man ufactur­ers. Use the UP and DOWN
buttons, as necessary, to highlight the appropriate manufacturer,
then press the ENTER/FF button to display the correct code
definition for your vehicle.

If the manufacturer for your vehicle is not listed, use the

UP and DOWN buttons, as necessary, to select
Other manufacturer and press the ENTER/FF but-

ton for additional DTC information.
If the Manufacturer Specific

definition for the currently dis­played code is not av ailab le, an
advisory message shows on
the Code Reader’s LCD dis­play.

10.If more than one code was retrieved press the DTC SCROLL

button, as necessary, to display additional codes one at a time.

■ Whenever the Scroll function is used to view additional codes,

the Code Reader’s communication link with the vehicle’s com­puter disconnects. To re-establish communication, press the

LINK button again.

40 CAN OBD2

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Using the Code Reader

CODE RETRIEVAL PROCEDURE

11.Freeze Frame Data (if av ailable) can be viewed at any time (except

MENU mode) by pressing the ENTER/FF button.

■ In OBD2 systems, when an emis-

sions-related engine malfunction
occurs that causes a DTC to set, a
record or snapshot of engine condi­tions at the time that the malfunction
occurred is also saved in the vehi­cle’s computer memory. The record
saved is called Freeze Frame data.
Saved engine conditions include, but are not limited to: engine
speed, open or closed loop operation, fuel system commands,
coolant temperature, calculated load value, fuel pressure, vehi­cle speed, air flow rate, and intake manifold pressure.

If more than one malfunction is present that causes more
than one DTC to be set, only the code with the highest pri­ority will contain Freeze Frame data.The code designated
“01” on the Code Reader display is referred to as the
PRIORITY code, and Freeze Frame data always refers to
this code.The priority code is also the one that has com­manded the MIL on.

If Freeze Frame data is not
available for the code shown
on the LCD display when the

ENTER/FF button

is
pressed, an advisory message
shows on the LCD display.
Press the DTC SCROLL
button to return to the previous
code display.

Retrieved information can be uploaded to a Personal
Computer (PC) with the use of an optional “PC Link Kit.”
For more information, visit us on the Web at
www

.canOBD2.com or call our ser vice department. See

Service Procedures on page 51 for more information.

12.Determine engine system(s) condition by viewing the Code

Reader’s LCD display for any retrieved Diagnostic Trouble Codes,
code definitions, Freeze Frame data and interpreting the green,
yellow and red LEDs.

■ If DTC’s were retrieved and you are going to perf orm the repairs

yourself, proceed by consulting the Vehicle’s Service Repair
Manual for testing instructions, testing procedures, and flow
charts related to retrieved code(s).

■ If you plan to take the vehicle to a professional to have it serv-

iced, complete the Preliminary Vehicle Diagnosis Worksheet
on page 30 and take it together with the retrieved codes, freeze
frame data and LED information to aid in the troubleshooting
procedure.

CAN OBD2 41

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■ To prolong battery life, the Code Reader automatically shuts

“Off” approximately three minutes after it is disconnected from
the vehicle.The DTCs retrieved, Monitor Status and F reeze F r ame
data (if any) will remain in the Code Reader’s memory, and may
be viewed at any time by turning the unit “On”. If the Code
Reader’s batteries are removed, or if the Code Reader is re­linked to a vehicle to retriev e codes/data, any prior codes/data in
its memory are automatically cleared.

ERASING DIAGNOSTIC TROUBLE CODES (DTCs)

When the Code Reader’s ERASE function is used to erase
DTCs from the vehicle's on-board computer, "Freeze
Frame" data and manufacturer-specific enhanced data
are also erased.

If you plan to take the vehicle to a Service Center for repair, DO NOT
erase the codes from the vehicle's computer. If the codes are erased,
valuable information that might help the technician troubleshoot the
problem will also be erased.

Erase DTCs from the computer's memory as follows:

When DTCs are erased from the vehicle's computer memo­ry, the I/M Readiness Monitor Status program resets the sta­tus of all Monitors to a not run "flashing" condition. To set all
of the Monitors to a DONE status, an OBD 2 Drive Cycle
must be performed.Refer to your vehicle's service manual for
information on how to perform an OBD 2 Drive Cycle for the
vehicle under test.

The Code Reader must be con­nected to the vehicle’s DLC to
erase the codes from the comput­er’s memory. If you press the
ERASE button when the
Code Reader is not connected to
the vehicle’s DLC, the erase
instruction screen displays.

1. If not connected already, connect the
Code Reader to the vehicle's DLC, and
turn the ignition "On.”(If the Code Reader
is already connected and linked to the
vehicle's computer, proceed directly to
step 4. If not, continue to step 2.)

2. Turn the ignition on. DO NOT star t the
engine. Press and release the
POWER/LINK button to establish
communication with the vehicle's com­puter.

Using the Code Reader

ERASING DIAGNOSTIC TROUBLE CODES (DTCs)

42 CAN OBD2

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Using the Code Reader

I/M READINESS TESTING

3. Press and release the ERASE but-

ton. A confir mation message shows on
the LCD display.

- If you are sure you want to proceed

press the ERASE button again to
erase DTCs from the vehicle’s com­puter.

- If you do not want to continue with the erase process, press the

POWER/LINK button to exit the erase mode.

4. If you chose to erase DTCs, a progress

screen displays while the erase function
is in progress.

■ If the erase was successful, a confir-

mation message shows on the LCD
display. Press the POWER/LINK

button to return to the DTC

screen.

■ If the erase was not successful, an

advisory message shows on the
LCD display. Verify that the Code
Reader is properly connected to the
vehicle’s DLC and that the ignition is
on, then repeat steps 2 and 3, abo ve .

Erasing DTCs does not fix the problem(s) that caused the
code(s) to be set.If proper repairs to correct the problem that
caused the code(s) to be set are not made, the code(s) will
appear again (and the check engine light will illuminate) as
soon as the vehicle is driven long enough for its Monitors to
complete their testing.

I/M READINESS TESTING

I/M is an Inspection and Maintenance program legislated by the
Government to meet federal clean-air standards.

The program requires that a vehicle be taken periodically to an
Emissions Station for an "Emissions Test" or "Smog Check,” where the
emissions-related components and systems are inspected and tested
for proper operation. Emissions Tests are generally performed once a
year, or once every two years.

On OBD 2 systems, the I/M program is enhanced by requiring vehicles to
meet stricter test standards. One of the tests instituted by the Federal
Government is called I/M 240. On I/M 240, the vehicle under test is driv­en under different speeds and load conditions on a dynamometer for 240
seconds, while the vehicle's emissions are measured.

CAN OBD2 43

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Emissions tests vary depending on the geographic or region­al area in which the vehicle is registered.If the vehicle is reg­istered in a highly urbanized area, the I/M 240 is probably the
type of test required.If the vehicle is registered in a rural area,
the stricter “dynamometer type” test may not be required.

I/M Readiness Monitors

I/M Readiness shows whether the various emissions-related systems
on the vehicle are operating properly and are ready for Inspection and
Maintenance testing.

State and Federal Gov ernments enacted Regulations, Procedures and
Emission Standards to ensure that all emissions-related components
and systems are continuously or periodically monitored, tested and
diagnosed whenever the vehicle is in operation. It also requires vehi­cle manufacturers to automatically detect and report any problems or
faults that may increase the v ehicle's emissions to an unacceptable lev el.

The vehicle's emissions control system consists of several compo­nents or sub-systems (Oxygen Sensor, Catalytic Conv erter, EGR, Fuel
System, etc.) that aid in reducing vehicle emissions.

To have an efficient Vehicle Emission Control System, all the emis­sions-related components and systems must work correctly whenever
the vehicle is in operation.

To comply with State and Federal Government regulations, vehicle
manufacturers designed a series of special computer programs called
"Monitors" that are programmed into the vehicle's computer. Each of
these Monitors is specifically designed to run tests and diagnostics on
a specific emissions-related component or system (Oxygen Sensor,
Catalytic Converter, EGR Valve, Fuel System, etc.) to ensure their
proper operation. Currently, there are a maximum of eleven Monitors
available for use.

Each Monitor has a specific function to test
and diagnose only its designated emissions­related component or system.The names of the
Monitors (Oxygen Sensor Monitor, Catalyst
Monitor, EGR Monitor, Misfire Monitor, etc.)
describe which component or system each Monitor
is designed to test and diagnose.

Using the Code Reader

I/M READINESS TESTING

To learn more about Emissions Inspection and Maintenance

(I/M) Readiness Monitors, see OBD 2 MONITORS on page 23.

44 CAN OBD2

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Emissions Inspection and Maintenance (I/M) Readiness

Monitor Status Inf

ormation

I/M Readiness Monitor Status shows which of the vehicle's Monitors
have run and completed their diagnosis and testing, and which ones
have not yet run and completed testing and diagnosis of their desig­nated sections of the vehicle's emissions system.

■ If a Monitor was able to meet all the conditions required to enable it

to perform the self-diagnosis and testing of its assigned engine sys­tem, it means the monitor "HAS RUN.”

■ If a Monitor has not yet met all the conditions required for it to per-

form the self-diagnosis and testing of its assigned engine system; it
means the Monitor "HAS NOT RUN.”

The Monitor Run/Not Run status does not show whether
or not a problem exists in a system. Monitor status only
indicates whether a particular Monitor has or has not run
and performed the self-diagnosis and testing of its asso­ciated system.

Performing I/M Readiness Quick Check

When a vehicle first comes from the factory, all Monitors indi­cate a “HAVE RUN” status. This indicates that all Monitors
have run and completed their diagnostic testing.The “HAVE
RUN” status remains in the computer's memory, unless the
Diagnostic Trouble Codes are erased or the vehicle's com­puter memory is cleared.

The Code Reader allows you to retrieve Monitor/System Status Infor­mation to help you determine if the vehicle is ready for an Emissions
Test (Smog Check). In addition to retrieving Diagnostic Trouble Codes,
the Code Reader also retrieves Monitor Run/Not Run status.This infor­mation is very important since different areas of the state/country have
different emissions laws and regulations concerning Monitor Run/Not
Run status.

Before an Emissions Test (Smog Check) can be performed, your vehi­cle must meet certain rules, requirements and procedures legislated
by the Federal and state (country) governments where you live.

1. In most areas, one of the requirements that must be met before a
vehicle is allowed to be Emissions Tested (Smog Checked) is that
the vehicle does not have any Diagnostic Trouble Codes present
(with the exception of PENDING Diagnostic Trouble Codes).

2. In addition to the requirement that no Diagnostic Trouble Codes be
present, some areas also require that all the Monitors that a partic­ular vehicle supports indicate a "Has Run" status condition before
an Emissions Check may be perfor med.

Using the Code Reader

I/M READINESS TESTING

CAN OBD2 45

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3. Other areas may only require that some (but not all) Monitors indi­cate a "Has Run" status before an Emissions Test (Smog Check)
may be performed.

Monitors with a "Has Run" status indicate that all the
required conditions they needed to perform diagnosis
and testing of their assigned engine area (system) have
been met, and all diagnostic testing has completed suc­cessfully.

Monitors with a "Has Not Run" status have not yet met
the conditions they need to perform diagnosis and test­ing of their assigned engine area (system), and have not
been able to perform diagnostic testing on that system.

The green, yellow and red LEDs provide a quic k wa y to help y ou deter­mine if a vehicle is ready for an Emissions Test (Smog Check). Follow
the instructions below to perform the Quick Check.

Perform the Code Retrieval Procedure as described on page 35,
then interpret the LED indications as follows:

Interpreting I/M Readiness Test Results

1. GREEN LED - Indicates that all engine

systems are "OK" and operating nor­mally (all Monitors supported by the
vehicle have run and performed their
self-diagnostic testing). The vehicle is
ready for an Emissions Test (Smog
Check), and there is a good possibility
that it can be certified.

2. YELLOW LED - Determine from the Code Retrieval Procedure
(page 35) which of the two possible conditions is causing the yellow
LED to light.

■ If a "PENDING" Diagnostic Trouble

Code is causing the yellow LED to
light, it is possible that the vehicle will
be allowed to be tested for emissions
and certified. Currently, most areas
(states / countries) will allow an
Emissions Test (Smog Check) to be
performed if the only code in the vehi­cle's computer is a "PENDING"
Diagnostic Trouble Code.

Using the Code Reader

I/M READINESS TESTING

46 CAN OBD2

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■ If the illumination of the Yellow LED is

being caused by monitors that “have
not run” their diagnostic testing, then
the issue of the vehicle being ready
for an Emissions Test (Smog Check)
depends on the emissions regula­tions and laws of your local area.

- Some areas require that all
Monitors indicate a "Has Run" status before they allow an
Emissions Test (Smog Check) to be performed. Other areas
only require that some, but not all, Monitors have run their
self-diagnostic testing before an Emissions Test (Smog
Check) may be perfor med.

From the code retrieval procedure, determine the status of
each Monitor (a solid Monitor icon shows Monitor "Has Run"
status, a flashing Monitor icon indicates "Has Not Run" sta­tus). Take this information to an emissions professional to
determine (based on your test results) if your vehicle is ready
for an Emissions Test (Smog Check).

3. RED LED - Indicates there is a problem
with one or more of the vehicle's sys­tems. A vehicle displaying a red LED is
definitely not ready for an Emissions
Test (Smog Check).The red LED is also
an indication that there are Diagnostic
Trouble Code(s) present (displayed on
the Code Reader's screen). The
Multifunction Indicator (Check Engine)
Lamp on the vehicle's instrument panel will light steady. The prob­lem that is causing the red LED to light must be repaired before an
Emissions Test (Smog Check) can be performed. It is also suggest­ed that the vehicle be inspected/repaired before driving the vehicle
further.

If the Red LED was obtained, there is a definite problem present in
the system(s). In these cases, you have the following options.

■ Repair the vehicle yourself. If you are going to perform the

repairs yourself, proceed by reading the vehicle service manual
and following all its procedures and recommendations.

■ Take the vehicle to a professional to have it ser viced. The prob-

lem(s) causing the red LED to light must be repaired before the
vehicle is ready for an Emissions Test (Smog Check).

Using the Code Reader

I/M READINESS TESTING

CAN OBD2 47

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Using the Code Reader

I/M READINESS TESTING

On some vehicle models, the computer will store non­emission related DTCs. These DTCs will not command the
MIL on since they are not emission related. If the Code
Reader retrieves one of these types of codes, the MIL will not
be commanded on, and the Yellow LED on the Code Reader
will be iluminated. In most cases, these types of codes will
not prevent the Emissions Test from being performed.

Using the I/M Readiness Monitor Status to Confirm a Repair

The I/M Readiness Monitor Status function can be used (after repair of
a fault has been performed) to confirm that the repair has been per­formed correctly, and/or to check for Monitor Run Status. Use the fol­lowing procedure to determine I/M Readiness Monitor Status:

1. Using retr ieved Diagnostic Trouble Codes (DTCs) and code defini­tions as a guide, and following manufacturer's repair procedures,
repair the fault or faults as instructed.

2. After the fault or faults have been repaired, connect the Code
Reader to the vehicle's DLC and erase the code or codes from the
vehicle's computer memory.

■ See page 41 f or procedures to erase DTCs from the v ehicle's on-

board computer.

■ Write the codes down on a piece of paper for reference before

erasing.

3. After the erase procedure is performed, most of the Monitor icons
on the Code Reader’s LCD display will be flashing. Leave the Code
Reader connected to the vehicle, and perform a T rip Drive Cycle for
each "flashing" Monitor:

Misfire, Fuel and Comprehensive Component Monitors run
continuously and their icons will always be on solid, even
after the erase function is performed.

■ Each DTC is associated with a specific Monitor.Consult the v ehi-

cle's service manual to identify the Monitor (or Monitors) associ­ated with the faults that were repaired.Follow the manufacturer's
procedures to perform a Trip Drive Cycle for the appropriate
Monitors.

■ While observing the Monitor icons on the Code Reader’s LCD

display, perform a Trip Drive Cycle for the appropriate Monitor or
Monitors.

48 CAN OBD2

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Using the Code Reader

I/M READINESS TESTING

If the vehicle needs to be driven in order to perform a Trip
Drive Cycle, ALWAYS have a second person help you.
One person should drive the vehicle while the other per­son observes the Monitor icons on the Code Reader for
Monitor RUN status. Trying to drive and observe the
Code Reader at the same time is dangerous, and could
cause a serious traffic accident.

4. When a Monitor's Trip Drive Cycle is performed properly, the

Monitor icon on the Code Reader’s LCD display changes from
"flashing" to "solid,” indicating that the Monitor has run and finished
its diagnostic testing.

■ If, after the Monitor has run, the MIL on the vehicle's dash is not

lit, and no stored or pending codes associated with that particu­lar Monitor are present in the vehicle's computer, the repair was
successful.

■ If, after the Monitor has run, the MIL on the vehicle's dash lights

and/or a DTC associated with that Monitor is present in the vehi­cle's computer, the repair was unsuccessful. Refer to the vehi­cle's service manual and recheck repair procedures.

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Glossary

GLOSSARY OF TERMS AND ABBREVIATIONS

INTRODUCTION

This Glossary contains definitions for abbreviations and terms you
may find in this manual or in your vehicle ser vice manual.

GLOSSARY OF TERMS AND ABBREVIATIONS

CARB – California Air Resources Board
CCM – Central Control Module
Computer Control System – An electronic control system, consisting

of an on-board computer and related sensors, switches and actuators,
used to ensure peak performance and fuel efficiency while reducing
pollutants in the vehicle’s emissions.

DIY – Do-It-Yourself
DLC – Data Link Connector
Drive Cycle – An extended set of driving procedures that takes into

consideration the various types of driving conditions encountered in
real life.

Driving Condition – A specific environmental or operation condition
under which a vehicle is operated; such as starting the vehicle when
cold, driving at steady speed (cruising), accelerating, etc.

DTC(s) – Diagnostic Trouble Code(s)
EGR – Exhaust Gas Recirculation
EPA – Environmental Protection Agency
EVAP – Evaporative Emissions System
Fault Code – See DTCs
Freeze Frame – A digital representation of engine and/or emissions

system conditions present when a fault code was recorded.

FTP – Fuel Tank Pressure
Generic Code – A DTC that applies to all OBD 2 compliant vehicles.
I/M Readiness – An indication of whether or not a vehicle’s emissions-

related system are operating properly and are ready for Inspection and
Maintenance testing.

I/M Test / Emissions Test / Smog Check – A functional test of a vehi­cle to determine if tailpipe emissions are within Federal/State/Local
requirements.

LCD – Liquid Cr ystal Display
LED – Light Emitting Diode
LTFT – Long Term Fuel Trim, is a program in the vehicle’s computer

designed to add or subtract fuel from the vehicle to compensate for
operating conditions that vary from the ideal A/F ratio (long term).

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Glossary

GLOSSARY OF TERMS AND ABBREVIATIONS

Manufacturer Specific Code – A DTC that applies only to OBD 2

compliant vehicles made by a specific manufacturer.
MIL – Malfunction Indicator Lamp (also referred to as “Check Engine”

light

OBD 1 – On-Board Diagnostics Version 1 (also referred to as “OBD I”)
OBD 2 – On-Board Diagnostics Version 2 (also referred to as “OBD II”)
On-Board Computer – The central processing unit in the vehicle’s

computer control system.

PCM – Powertrain Control Module
Pending Code – A code recorded on the “first trip” for a “two-trip”

code. If the fault that caused the code to be set is not detected on the
second trip, the code is automatically erased.

STFT – Shor t Term Fuel Trim, is a program in the vehicle’s computer
designed to add or subtract fuel from the vehicle to compensate for
operating conditions that vary from the ideal A/F ratio.The vehicle uses
this program to make minor fuel adjustments (fine tune) on a short­term basis.

T rip Drive Cycle – Vehicle operation that provides the necessary driv­ing condition to enable a vehicle Monitor to run and complete its diag­nostic testing.

VECI – Vehicle Emission Control Information Decal

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Warranty and Servicing

LIMITED ONE YEAR WARRANTY

The Manufacturer warrants to the original purchaser that this unit is
free of defects in materials and workmanship under normal use and
maintenance for a period of one (1) year from the date of original pur­chase.

If the unit fails within the one (1) year period, it will be repaired or
replaced, at the Manufacturer’s option, at no charge, when returned
prepaid to the Service Center with Proof of Purchase. The sales
receipt may be used for this purpose. All replacement parts, whether
new or re-manufactured, assume as their warranty period only the
remaining time of this warranty.

This warranty does not apply to damage caused by improper use, acci­dent, abuse, improper voltage, service, fire, flood, lightning, or other
acts of God, or if the product was altered or repaired by anyone other
than the Manufacturer’s Service Center.

The Manufacturer, under no circumstances shall be liable for any con­sequential damages for breach of any written warranty of this unit.This
warranty gives you specific legal rights, and you may also have rights
which vary from state to state.This manual is copyrighted with all rights
reserved.No portion of this document may be copied or reproduced b y
any means without the express written permission of the Manufacturer .
THIS WARRANTY IS NOT TRANSFERABLE. For service, send via
U.P.S. (if possible) prepaid to Manufacturer. Allow 3-4 weeks for
service/repair.

SERVICE PROCEDURES

If you have any questions, please contact your local store, distributor
or the Service Center.

USA & Canada:

[phone] (9:00-4:00, Monday-Friday PST)

All others: [phone] (9:00-4:00, Monday-Friday PST)
FAX: [phone] (24 hr.)

For technical support and information on UPDATES and OPTIONAL
ACCESSORIES, visit on the W eb at www

.CanOBD2.com or contact us
through Fax: [phone]; Phone: [phone] or (714) 241­6805 (7AM-4PM Pacific Standard Time).

Notes

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Notes

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®

Innova Electronics Corp.

PRODUCT DESIGN & COPYRIGHT

17291 Mt. Herrmann Street
Fountain Valley, CA 92708
Printed in Taiwan

Instruction MRP #93-0036

© 2004