Equus 3100 User Manual
Table of Contents
INTRODUCTION
WHAT IS OBD? ........................................................................ 1
YOU CAN DO IT! ..............................................................................
SAFETY PRECAUTIONS
SAFETY FIRST! ........................................................................ 3
ABOUT THE DIAGNOSTIC TOOL
VEHICLES COVERED ............................................................. 5
BATTERY REPLACEMENT ..................................................... 6
ADJUSTMENTS/SETTINGS AND DTC LIBRARY .................. 6
DIAGNOSTIC TOOL CONTROLS
CONTROLS AND INDICATORS ............................................. 11
DISPLAY FUNCTIONS ............................................................ 13
ONBOARD DIAGNOSTICS
COMPUTER ENGINE CONTROLS ......................................... 15
DIAGNOSTIC TROUBLE CODES (DTCs) .............................. 20
OBD2 MONITORS .................................................................... 23
PREPARATION FOR TESTING
PRELIMINARY VEHICLE DIAGNOSTIC WORKSHEET ......... 32
BEFORE YOU BEGIN .............................................................. 35
VEHICLE SERVICE MANUALS ............................................... 36
USING THE DIAGNOSTIC TOOL
CODE RETRIEVAL PROCEDURE .......................................... 37
THE ENHANCED MAIN MENU ................................................ 43
VIEWING ENHANCED DTCs .................................................. 45
VIEWING VEHICLE INFORMATION ....................................... 50
ERASING DIAGNOSTIC TROUBLE CODES (DTCs) ............. 51
I/M READINESS TESTING ...................................................... 53
GLOSSARY
INTRODUCTION ....................................................................... 59
GLOSSARY OF TERMS AND ABBREVIATIONS ................... 59
WARRANTY AND SERVICING
LIMITED ONE YEAR WARRANTY .......................................... 61
SERVICE PROCEDURES ....................................................... 61
2
i OBD2
Introduction
WHAT IS OBD?
WHAT IS OBD?
The Enhanced CanOBD2 Diagnostic Tool is designed to work on
all OBD2 compliant vehicles. All 1996 and newer vehicles (cars,
light trucks and SUVs) sold in the United States are OBD2
One of the most exciting improvements in the
automobile industry was the addition of onboard diagnostics (OBD) on vehicles, or in more
basic terms, the computer that activates the
vehicle’s “CHECK ENGINE” light. OBD1 was
designed to monitor manufacturer-specific
systems on vehicles built from 1981 to 1995.
Then came the development of OBD2, which is
on all 1996 and newer vehicles sold in the U.S. Like its predecessor,
OBD2 was adopted as part of a government mandate to lower vehicle
emissions. But what makes OBD2 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
OBD2 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 Enhanced CanOBD2 Diagnostic Tool, is required to retrieve
these codes, which consumers and professionals use as a starting point
for repairs.
The Enhanced CanOBD2 Diagnostic Tool provides the additional ability
to retrieve enhanced DTCs from most Chrysler/Jeep, Ford/Mazda and
GM/Isuzu vehicles. The types of enhanced data available depends on
the vehicle make.
compliant.
To learn more about vehicle Computer Control Systems and
OBD2, see COMPUTER ENGINE CONTROLS on page 14.
OBD2 1
You Can Do It!
EASY TO USE - EASY TO VIEW - EASY TO DEFINE
Easy To Use . . . .
Connect the Diagnostic Tool to the
vehicle’s test connector.
Turn the ignition key "On.”
Press the LINK button.
Easy To View . . . .
The Diagnostic Tool retrieves stored
codes, Freeze Frame data and I/M
Readiness status.
Codes, I/M Readiness status and
Freeze Frame data are displayed on the
Diagnostic Tool’s LCD display screen.
System status is indicated by LED
indicators.
Easy To Define . . . .
Read code definitions from the
Diagnostic Tool’s LCD display.
View Freeze Frame data.
2 OBD2
Safety Precautions
SAFETY FIRST!
SAFETY FIRST!
To avoid personal injury, instrument damage and/or
damage to your vehicle; do not use the OBD2 Code Reader
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 prevent 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.
before reading this manual.
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 troubleshooting,
N
R
P
make sure the parking brake is engaged. Put the
D
L
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 Diagnostic Tool to or disconnecting
the Diagnostic Tool from the vehicle’s Data Link Connector
(DLC).
OBD2 3
Safety Precautions
SAFETY FIRST!
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.
4 OBD2
About the Diagnostic Tool
VEHICLES COVERED
VEHICLES COVERED
The Enhanced CanOBD2 Diagnostic Tool is designed to work on all
OBD2 compliant vehicles. All 1996 and newer vehicles (cars and light
trucks) sold in the United States are OBD2 compliant.
Federal law requires that all 1996 and newer cars and light
trucks sold in the United States must be OBD2 compliant; this
includes all Domestic, Asian and European vehicles.
Some 1994 and 1995 vehicles are OBD2 compliant. To find out if a
1994 or 1995 vehicle is OBD2 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 OBD2 compliant, the label will state “OBD II
Certified.”
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
2. Government Regulations require that all
OBD2 compliant vehicles must have a
“common” sixteen-pin Data Link
12345678
9 10111213141516
Connector (DLC).
Some 1994 and 1995 vehicles have 16-pin connectors but are
not OBD2 compliant. Only those vehicles with a Vehicle
Emissions Control Label stating “OBD II Certified” are OBD2
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.
LEFT CORNER
OF DASH
NEAR
CENTER
OF DASH
BEHIND
ASHTRAY
OBD2 5
About the Diagnostic Tool
BATTERY REPLACEMENT / ADJUSTMENTS/SETTINGS AND DTC LIBRARY
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
Replace batteries when the battery symbol is visible on display
and/or the 3 LEDS are all lit and no other data is visible on screen.
1. Locate the battery cover on the back of the Diagnostic Tool.
2. Slide the battery cover off (use your fingers).
3. Replace batteries with two AA-size batteries (for longer life, use
Alkaline-type batteries).
4. Reinstall the battery cover on the back of the Diagnostic Tool.
Language Selection After Battery Installation
The first time the unit is turned on, you must select the desired display
language (English, French or Spanish) as follows:
1. Press the POWER/LINK
turn the Diagnostic Tool “ON.”
The Select Language screen
displays.
2. Use the UP
buttons, as necessary, to highlight the
desired display language.
3. When the desired display language is selected, press the
ENTER/FF
After the initial language selection is performed, it, as well as
other settings, can be changed as desired. Proceed to
“ADJUSTMENTS/SETTINGS AND DTC LIBRARY” below for
further instructions.
and DOWN
button to confirm your selection.
button to
ADJUSTMENTS/SETTINGS AND DTC LIBRARY
The Diagnostic Tool lets you make several adjustments and settings to
configure the Diagnostic Tool to your particular needs. It also contains
an OBD2 DTC Library that allows you to search for DTC definitions. The
following functions, adjustments and settings can be performed when
the Diagnostic Tool is in “MENU Mode”:
Adjust Brightness: Adjusts the brightness of the LCD display
screen.
DTC Library: Lets you search the library of OBD2 DTC definitions.
6 OBD2
About the Diagnostic Tool
ADJUSTMENTS / SETTINGS AND DTC LIBRARY
Select Language: Sets the display language for the Diagnostic Tool
to English, French or Spanish.
Unit of Measurement: Sets the Unit of Measurement for the
Diagnostic Tool’s display to USA or metric.
Adjustments and settings can be made only when the
Diagnostic Tool is NOT connected to a vehicle.
To enter the MENU Mode:
1. With the Diagnostic Tool OFF, press
and hold the UP
and release the POWER/LINK
button.
The adjustments and setting MENU
displays.
2. Release the UP
DO NOT release the UP
settings MENU is visible on the display.
3. Make adjustments and settings as described in the following
paragraphs.
Adjusting Display Brightness
button, then press
button.
button until the adjustments and
1. Use the UP
and DOWN buttons,
as necessary, to highlight Adjust
Brightness in the MENU, then press
the ENTER/FF
The Adjust Brightness screen dis-
button.
plays.
The Brightness field shows the current brightness setting, from
1 to 8.
2. Press the UP
button to decrease the
brightness of the LCD display (make the
display darker).
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.
OBD2 7
About the Diagnostic Tool
ADJUSTMENTS / SETTINGS AND DTC LIBRARY
Searching for a DTC Definition Using the DTC Library
1. Use the UP
and DOWN buttons,
as necessary, to highlight DTC Library
in the MENU, then press the ENTER/FF
button.
The Enter DTC screen displays. The
screen shows the code “P0001”,
with the “P” flashing.
2. Use the UP
and DOWN buttons,
as necessary, to scroll to the desired
DTC type (P=Powertrain, U=Network,
B=Body, C=Chassis), then press the
DTC SCROLL
The selected character displays “solid”,
button.
and the next character begins flashing.
3. Select the remaining characters in the DTC in the same way,
pressing the DTC SCROLL
button to confirm each character.
When you have selected all the DTC characters, press the
ENTER/FF
If you entered a “Generic” DTC
button to view the DTC definition.
(DTCs that start with “P0”, “P2” and
some “P3”):
- The selected DTC and DTC
definition (if available), show on
the Diagnostic Tool’s LCD display.
If you entered a “Manufacturer-
Specific” DTC (DTCs that start with
“P1” and some “P3”):
- The “Select Manufacturer” screen
displays.
- Use the UP
and DOWN
buttons, as necessary, to highlight
the appropriate manufacturer, then press the ENTER/FF
button to display the correct DTC for your vehicle. A
confirmation message shows on the LCD display.
- If the correct manufacturer is
shown, press the ENTER/FF
button to continue.
- If the correct manufacturer is not
shown, press the DTC SCROLL
button to return to the list of
vehicle manufacturers.
8 OBD2
About the Diagnostic Tool
ADJUSTMENTS / SETTINGS AND DTC LIBRARY
If a definition for the DTC you
entered is not available, an
advisory message shows on the
Enhanced CanOBD2 Diagnostic
Tool’s display.
4. If you wish to view definitions for additional DTCs, press the
ENTER/FF
repeat steps 2 and 3.
5. When all desired DTCs have been viewed, press the ERASE
button to exit the DTC Library.
Selecting the Display Language
button to return to the DTC Library screen, and
1. Use the UP
and DOWN buttons,
as necessary, to highlight Select
Language in the MENU, then press the
ENTER/FF
The Select Language screen dis-
button.
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 high-
lighted, press the ENTER/FF
button to
save your changes and return to the MENU
(shown in the selected display language).
Setting the Unit of Measure
1. Use the UP
and DOWN buttons,
as necessary, to highlight Unit of
Measure in the MENU, then press the
ENTER/FF
2. Press the UP
button.
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.
OBD2 9
About the Diagnostic Tool
ADJUSTMENTS / SETTINGS AND DTC LIBRARY
Exiting the MENU Mode
1. Use the UP
Menu Exit in the MENU, then press the ENTER/FF
The LCD display returns to the DTC screen (if data is currently
and DOWN buttons, as necessary, to highlight
button.
stored in the Diagnostic Tool’s memory) or the “To Link” screen
(if no data is stored).
10 OBD2
Diagnostic Tool Controls
CONTROLS AND INDICATORS
CONTROLS AND INDICATORS
7
6
1
2
5
11
10
8
9
3
4
Figure 1. 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 Diagnostic Tool IS NOT
connected to a vehicle, turns the Diagnostic Tool “On” and “Off”.
When the Diagnostic Tool is connected to a vehicle, links the
Diagnostic Tool to the vehicle’s PCM to retrieve diagnostic data from
the computer’s memory.
To turn the Diagnostic Tool "On", you must press and hold the
POWER/LINK
4.
ENTER/FREEZE FRAME button - When in MENU mode,
confirms the selected option or value. When retrieving and viewing
button for approximately 3 seconds.
DTCs, displays Freeze Frame data for the highest priority code.
OBD2 11
Diagnostic Tool Controls
CONTROLS AND INDICATORS
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.
UP button - When in MENU mode, scrolls UP through the menu
6.
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 running
normally (all Monitors on the vehicle are active and performing 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 Diagnostic Tool’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,
Diagnostic Tool functions and Monitor status information. See
DISPLAY FUNCTIONS, on next page, for more details.
11. CABLE - Connects the Diagnostic Tool to the vehicle’s Data Link
Connector (DLC).
12 OBD2
Diagnostic Tool Controls
DISPLAY FUNCTIONS
DISPLAY FUNCTIONS
21
3
4
5
6
7
8
Figure 2. Display Functions
See Figure 2 for the locations of items 1 through 16, below.
1. I/M MONITOR STATUS field - Identifies the I/M Monitor status area.
2. Monitor icons - Indicate which Monitors are supported by the
vehicle 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 Diagnostic Tool is
being properly powered through the vehicle’s Data Link Connector
(DLC). A visible icon indicates that the Diagnostic Tool is being
powered through the vehicle’s DLC connector.
Link icon - Indicates whether or not the Diagnostic Tool is
4.
communicating (linked) with the vehicle’s on-board computer. When
visible, the Diagnostic Tool is communicating with the computer. If
the Link icon is not visible, the Diagnostic Tool is not communicating
with the computer.
Computer icon - When this icon is visible it indicates that the
5.
Diagnostic Tool 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.
Diagnostic Tool Internal Battery icon - When visible, indicates
6.
the Diagnostic Tool batteries are “low” and should be replaced. If the
batteries are not replaced when the battery symbol
LEDs will light up as a last resort indicator to warn you that the
batteries need replacement. No data will be displayed on screen
when all 3 LEDs are lit.
11
12 13
14
10
9
is "on", all 3
OBD2 13
Diagnostic Tool Controls
DISPLAY FUNCTIONS
7. DTC Display Area - Displays the Diagnostic Trouble Code (DTC)
number. Each fault is assigned a code number that is specific to that
fault.
8. Test Data Display Area - Displays DTC definitions, Freeze Frame
data, and other pertinent test information messages.
9. FREEZE FRAME icon - Indicates that there is Freeze Frame data
from “Priority Code” (Code #1) stored in the vehicle’s computer
memory.
10. PERMANENT icon - Indicates the currently displayed DTC is a
“Permanent” code.
11. PENDING icon - Indicates the currently displayed DTC is a
“Pending” code.
12. 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.
13. Code Number Sequence - The Diagnostic Tool 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.
14. Code Enumerator - Indicates the total number of codes retrieved
from the vehicle’s computer.
14 OBD2
Onboard Diagnostics
COMPUTER ENGINE CONTROLS
COMPUTER ENGINE CONTROLS
The Introduction of Electronic Engine Controls
Electronic Computer Control Systems make it possible
for vehicle manufacturers to comply with the tougher
emissions and fuel efficiency standards mandated by
State and Federal Governments.
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 fuel-efficient. 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.
OBD2 15
Onboard Diagnostics
COMPUTER ENGINE CONTROLS
The Basic Engine Computer Control System
The Computer Control System consists of an on-board
computer and several related control devices (sensors,
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 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 reference 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 perform these actions.
OUTPUT DEVICES
Fuel Injectors
Idle Air Control
EGR Valve
Ignition Module
switches, and actuators).
TYPICAL COMPUTER
CONTROL SYSTEM
On-Board
Computer
INPUT DEVICES
Coolant Temperature Sensor
Throttle Position Sensor
Fuel Injectors
INPUT DEVICES
Oxygen Sensors
16 OBD2
Onboard Diagnostics
COMPUTER ENGINE CONTROLS
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 (OBD1)
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.
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 program would be
capable of identifying emissions-related faults in a system. The
first generation of Onboard Diagnostics came to be known as
OBD1.
OBD1 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.”
On-Board Diagnostics - Second Generation (OBD2)
In addition to performing all the
functions of the OBD1 System, the
OBD2 System has been enhanced with
new Diagnostic Programs. These
programs closely monitor the functions
The OBD2 System is
an enhancement of the
OBD1 System.
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 OBD1 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.
OBD2 17
Onboard Diagnostics
COMPUTER ENGINE CONTROLS
Because OBD1 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 new vehicles with
devices 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
(OBD2).” The primary objective of the OBD2 system is to comply with
the latest regulations and emissions standards established by CARB
and the EPA.
The Main Objectives of the OBD2 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.
To use a standardized Diagnostic Link Connector (DLC) in all
vehicles. (Before OBD2, DLCs were of different shapes and sizes.)
To standardize the code numbers, code definitions and language
used to describe faults. (Before OBD2, 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.
OBD2 Terminology
The following terms and their definitions are related to OBD2 systems.
Read and reference this list as needed to aid in the understanding of
OBD2 systems.
18 OBD2
Loading...