Equus 3145 User Manual

FORD DIGITAL

CODE READER

(Front Cover)

Table of Contents

Title Page No.

YOU CAN DO IT! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

CHAPTER 1 - GENERAL INFORMATION

SAFETY PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

HOW TO USE THIS MANUAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

VEHICLE SERVICE MANUALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

VEHICLES COVERED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

PRELIMINARY VEHICLE DIAGNOSIS WORKSHEET . . . . . . . . . . . . . . . . . 8

CHAPTER 2 - ABOUT DIAGNOSTIC SYSTEMS

WHAT ARE THE ADVANTAGES OF USING COMPUTER CONTROL

SYSTEMS ON VEHICLES? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

HOW DOES A COMPUTER SYSTEM WORK ON A VEHICLE, AND

WHAT IS IT’S MAIN PURPOSE? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

HISTORY OF FORDS ELECTRONIC ENGINE CONTROL (EEC)

SYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

FORD COMPUTER SYSTEM OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

CHAPTER 3 - ABOUT THE FORD CODE READER

BEFORE YOU BEGIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

TEST CONNECTORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

CONNECTING THE FORD CODE READER TO THE VEHICLE’S

TEST CONNECTOR(S) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

FUNCTIONS OF THE FORD CODE READER . . . . . . . . . . . . . . . . . . . . . . . . . . 19

CHAPTER 4 - RETRIEVING CODES

OVERVIEW OF FAULT CODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

OVERVIEW OF FORD CODE RETRIEVAL PROCESS . . . . . . . . . . . . . . . . . 24

KEY ON ENGINE OFF (KOEO) TEST PROCEDURES

(EEC-IV SYSTEMS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

ENGINE TIMING CHECK (EEC-IV SYSTEMS) . . . . . . . . . . . . . . . . . . . . . . . 30

KEY ON ENGINE RUNNING (KOER) SELF TEST (EEC-IV SYSTEMS) . . . . 32

ERASING CODES FROM EEC-IV SYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . . 37

ADDITIONAL TESTS FOR EEC-IV SYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . 38

FAULT CODE DEFINITIONS FOR EEC-IV SYSTEMS CAR AND

TRUCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

RETRIEVING FAULT CODES FROM MCU SYSTEMS . . . . . . . . . . . . . . . . . 65

KEY ON ENGINE OFF (KOEO) SELF TEST (MCU SYSTEMS) . . . . . . . . . . 66

KEY ON ENGINE RUNNING (KOER) SELF TEST (MCU SYSTEMS) . . . . . 68

FAULT CODE DEFINITIONS FOR MCU SYSTEMS CAR AND TRUCK . . . . 71

CHAPTER 5 - TROUBLESHOOTING

CODE READER TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . 75

CHAPTER 6 - GLOSSARY

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

GLOSSARY OF TERMS AND ABBREVIATIONS . . . . . . . . . . . . . . . . . . . . . . 77

CHAPTER 7 - WARRANTY AND SERVICE

LIMITED ONE YEAR WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

SERVICE PROCEDURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

i

You Can Do It!

ii

1

Plug It In

•

Ensure ignition is off.

•

Plug Code Reader into test
connector (test connector is
usually found under the
hood).

2

Read Fault Codes

•

Turn on ignition. DO NOT
START ENGINE.

•

Turn Code Reader ON.

•

Press TEST/HOLD button
and read codes.

3

Pinpoint Problem Areas

•

Locate fault code(s) in the
appropriate Code Definition
List.

L

Co

o

ms

nj

2

t

r
d

Se

VS

m

This is a brief introduction only. Read this manual
for a complete description of the Code Reader and
its proper operation.

MEMORY ON / OFF

TEST / HOLD

INCOLN MERCURY

es 1981 to 1995

O

TEST / HOLD

MEMORY ON / OFF

ving

E DEFINITION

r Crankshaft sensor - circuit proble

ector circuit is not working properly ­le blown fuel injector fuse

nition system fault - Intermittent 7X signal or

loss of 58X signal or 6X signal (Saturn)

Throttle position sensor (TPS) - signal voltage is

high during engine idle or deceleration

low during engine idle

Fuel cutoff relay circuit - open or shorted

ground

2 Throttle position sensor (TPS) - signal voltage is

voltage is low or high

Throttle position sensor (TPS) erro

Mixture Control (M/C) solenoi

23 Manifold air temperature (MAT) sensor

circuit problems

ntake Air Temperature

icle

speed sensor (

s

air te

General Information

SAFETY PRECAUTIONS

1 Chapter 1

SAFETY PRECAUTIONS

To avoid personal injury, instrument damage and/or
damage to equipment under test; do not operate the
Ford Digital Code Reader before reading this manual.

This manual describes common test procedures used by
experienced service personnel and technicians. Many test
procedures require precautions to avoid accidents that can
result in personal injury, and/or vehicle or equipment damage.
Always read your vehicle’s service manual and follow its safety
precautions before any test or service procedure is performed.

a. 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 a vehicle
ONLY in a well-ventilated area.

b. To protect your eyes from propelled objects as well as hot

or caustic liquids, always wear approved safety eye
protection.

c. When an engine is running, several objects rotate at a

very high rate of speed (cooling fan, pulleys, fan belt etc.).
To avoid serious injury, always be conscious of moving
parts, and keep a safe distance from all these items as
well as other potentially moving objects.

d. Engine parts become extremely hot when the engine is

running. To prevent severe burns, avoid contact with hot
engine parts.

e. Before starting an engine for troubleshooting, 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 a
suitable blocking device.

f. Connecting or disconnecting test equipment when the

ignition is “on” can cause a spark. This spark is
potentially damaging to the test equipment and to the
vehicle’s electronic components. Always turn the ignition
“off” before connecting or disconnecting any test
equipment.

g. 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.

1

General Information

HOW TO USE THIS MANUAL

Chapter 1 2

h. The vehicle’s battery produces highly flammable hydrogen

gas. To prevent an explosion, keep all sparks, high
temperature items or open flames away from the battery.

i. Don't wear loose clothing or jewelry when working on an

engine. Loose clothing can get caught on 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.

INTRODUCTION

Congratulations, you have purchased one of the most
technologically advanced Code Readers on the market today.
The Ford Digital Code Reader uses sophisticated electronics
designed to retrieve engine and transmission (applicable Ford
vehicles only) Diagnostic Trouble Codes (DTC's) from the
vehicle's computer.

HOW TO USE THIS MANUAL

This Code Reader and manual are designed for use both by
consumers with little or no experience in retrieving codes, or by
experienced technicians desiring a more in-depth explanation
of Ford Computer Command Control system basics.

If you are having problems with your vehicle and only want to
know if any Diagnostic Trouble Codes are present in the vehicle’s
computer system, read the “Safety Precautions” (page 1) and
“Vehicles Covered” (page 4), then proceed to Chapter 3 and follow
the simple directions to retrieve the codes. The codes retrieved,
and their definitions, will give you valuable information and a
starting point from which to proceed to the next step.

Once the codes have been retrieved, you can choose to:

•

Take your vehicle to an Automotive Service Center
for repair: Take your vehicle, a copy of the completed

Preliminary Vehicle Diagnosis Worksheet (see pages 8 - 10)
and codes retrieved to your technician for evaluation. This
will demonstrate to your technician that you are an
informed motorist and will also assist him in pinpointing
the location of the problem.

1

General Information

VEHICLE SERVICE MANUALS

3 Chapter 1

•

Attempt to fix the problem yourself: If you choose to

fix the problem yourself, read and follow all of the
manual’s recommendations and procedures. Additional
tools, text equipment (multimeter, timing light, etc.) and a
vehicle repair manual containing Ford’s Diagnostic Trouble
Code Service Procedures for your vehicle will be needed.

VEHICLE SERVICE MANUALS

It is recommended that you consult the manufacturer’s service
manual for your vehicle before any test or repair procedures
are performed.

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]

1

General Information

VEHICLES COVERED - CARS

Chapter 1 4

VEHICLES COVERED
CAR

- Ford, Lincoln, Mercury Computer System/Code Reader

Application Table

The following table is applicable to all models (excluding
Diesel) of Ford, Lincoln and Mercury vehicles.

Fuel Systems

8th VIN (Carburetor Computer

Engine Digit** Model) Application/Special Notes System

1981-1982

2.3L I-4 OHC A FBC Capri, Cougar, Fairmont, MCU
(6500-2V)* Granada, Mustang, Zephyr

3.8L V-6 3 FBC Continental, Cougar, Granada,

(7200 VV-2V)* T-Bird (Cal. only)

4.2L V-8 D Capri, Cougar, Fairmont,

Granada, Mark VII, Mustang,
T-Bird, Zephyr

5.0L V-8 F Capri, Continental (Cal. only),

Granada, Mark VII, Mustang

5.8L V-8 G All Federal Police models

1983

2.3L I-4 OHC A FBC Capri, Fairmont, LTD, Marquis, MCU
(6500-2V)* Mustang

3.8L V-6 3 FBC Continental, Cougar, Granada,

(7200-VV-2V)* T-Bird (Cal. only)

5.0L V-8 F

Capri, Continental, Cougar,

5.8L V-8 G

Fairmont, Granada, Mark VII,
Mustang, T-Bird, Zephyr

1.6L I-4 5, 2 EFI, EFI Turbo Escort, EXP, LN7, Lynx EEC-IV

2.3L I-4 5 EFI Turbo Capri, Cougar, Mustang, T-Bird

2.3L I-4 HSC R, J FBC (6149)* Capri, Fairmont, LTD, Marquis,

Mustang, Tempo, Topaz, Zephyr

1984-1986

5.8L V-8 G FBC Crown Victoria, Grand Marquis MCU

(7200-VV-2V)*

1.6L I-4 4, 5 EFI Escort, EXP, Lynx EEC-IV

8 EFI Turbo

2.3L I-4 A, J, R FBC Capri, Cougar, LTD, Marquis,

2.3L I-4 OHC (YFA)* (6149)* Mustang, Tempo, Topaz

2.3L I-4 T, W EFI Turbo Capri, Cougar, Merkur XR4Ti,

Mustang, T-Bird

2.3L I-4 HSC S, X CFI Tempo, Topaz

3.8L V-6 3 CFI Capri, Cougar, LTD, Marquis,

Mustang, T-Bird

5.0L V-8 F, M CFI, SEFI Capri, Continental, Colony Park,

Cougar, Country Squire, Crown
Victoria, Grand Marquis, LTD,
Mark VII, Marquis, Mustang,
T-Bird, Town Car

1

General Information

VEHICLES COVERED - CARS

5 Chapter 1

Fuel Systems

8th VIN (Carburetor Computer

Engine Digit** Model) Application/Special Notes System

1987-1993

5.8L V-8 G FBC 1987-91 Police vehicles only MCU

(7200 VV-2V)* (carbureted)

1.9L I-4 J, 9 EFI, CFI, SFI Escort, EXP, Lynx, Tracer EEC-IV

2.0L I-4 A SEFI Probe (1993 manual transmis-

sion only)

2.3L I-4 A FBC (YFA)* Capri, LTD, Marquis, Mustang

(1996 models)

2.3L I-4 OHC A, M EFI Mustang

2.3L I-4 T, W EFI Turbo Capri, Cougar, Merkur,

Mustang, T-Bird, XR4Ti

2.3L I-4 HSC S, X CFI, EFI, SEFI Tempo, Topaz

2.5L I-4 D EFI, CFI Sable, Taurus

3.0L V-6 1, U, Y EFI, SEFI, SFI Probe, Sable, Taurus, Tempo,

3.0L V-6 SHO Topaz (VIN 1 Taurus models are

Flexible Fuel)

3.8L V-6 3, 4, C, R CFI, EFI, SFI Capri, Continental, Cougar,

LTD, Marquis, Mustang, Sable,
T-Bird,Taurus

4.6L V-8 W, V SEFI Crown Victoria, Grand Marquis,

Mark VII, Town Car

5.0L V-8 F, M, E, SEFI Capri, Continental, Cougar,

T, D, 4 Crown Victoria, Grand Marquis,

Mark VII, Mustang, Mustang
Cobra, T-Bird, Town Car

1994

1.9L I-4 J SFI Escort, Topaz, Tracer EEC-IV

2.0L I-4 A SFI Probe

3.0L V-6 1, U, Y SFI Sable, Taurus, Tempo (VIN 1

Taurus models are Flexible Fuel)

3.8L V-6 4 SFI Continental, Cougar, Sable,

3.8L V-6 SC R Taurus, T-Bird

4.6L V-8 W, V SFI Crown Victoria, Grand Marquis,

Mark VIII, Town Car

5.0L V-8 T, D SFI Mustang, Mustang Cobra

1995

1.9L I-4 J SFI Escort, Tracer EEC-IV

2.0L I-4 A, 3 SFI Contour, Mystique, Probe

2.5L V-6 L SFI Contour, Mystique

3.0L V-6 1, U SFI Sable, Taurus (VIN 1 Taurus

3.0L V-6 SHO Y

models are Flexible Fuel)

3.8L V-6 4 SFI Cougar, Sable, Taurus, T-Bird

3.8L V-6 SC R

4.6L V8 DOHC V SFI Mark VIII

5.0L V-8 HO T SFI Mustang

5.0L V-8 SHP D

1

General Information

VEHICLES COVERED - TRUCKS/VANS

Chapter 1 6

TRUCKS/VANS - Ford Computer System Code Reader

Application Table

The following table is applicable to all models of Trucks, Vans
and Utility Vehicles.

NOTES

* Carburetor Model. Carburetor model numbers are usually stamped on top of the

carburetor, or on a metal tab attached to the carburetor. Consult your vehicle’s repair
manual for proper identification.

**VIN Number. The VIN number(s) used in this column identify the vehicle’s engine
type. This number is the 8th digit of the VIN (Vehicle Identification Number). Consult
your vehicle’s repair manual for details.

Application Table Definitions. CFI = Central Fuel Injection; DOHC = Dual
Overhead Cam; EFI = Electronic Fuel Injection; FBC = Feedback Carburetor; HSC =
High Swirl Combustion; MFI = Multiport Fuel Injection; OHC = Overhead Cam; SC =
Super Charged; SEFI = Sequential Electronic Fuel Injection; SFI = Sequential Fuel
Injection; SHO = Super High Output

Fuel Systems

8th VIN (Carburetor Computer

Engine Digit** Model) Application/Special Notes System

1981-1982

4.9L I-6 E FBC (YFA)* Bronco (Cal. only); E and F MCU

Series Trucks/Vans

1983

2.0L I-4 C FBC (2150A)* Ranger Pickup MCU

2.3L I-4 OHC A FBC (YFA)* Ranger Pickup (excluding high

altitude)

4.9L I-6 E FBC (YFA)* Bronco (Cal. only), E and F

Series Trucks/Vans (8500 lb.
GVW or less only)

2.8L V-6 S FBC (2150A)* Bronco II and Ranger Pickup EEC-IV

1984

2.0L I-4 C FBC (YFA)* Ranger Pickup MCU

2.3L I-4 OHC A FBC (YFA)*

2.8L V-6 S FBC (2150A)* Bronco II, Ranger Pickup EEC-IV

4.9L I-6 Y FBC (YFA)* Bronco, E and F Series Trucks/

5.0L V-8 F FBC (2150A)*

Vans (8500 lb. GVW or less only)

5.8L V-8 G FBC (2150A)*

1985-1990

2.3L I-4 OHC A EFI Aerostar, Bronco II, Ranger EEC-IV

2.9L V-6 T EFI

(excluding Diesel)

2.8L V-6 S FBC (2150A)* Bronco, E and F Series Trucks/

4.9L I-6 Y, 9 FBC (YFA)*,

Vans (8500 lb. GVW or less only)

EFI

5.0L V-8 F FBC (2150A)*

5.0L V-8 N EFI

1

General Information

VEHICLES COVERED - TRUCKS/VANS

7 Chapter 1

Fuel Systems

8th VIN (Carburetor Computer

Engine Digit** Model) Application/Special Notes System

1985-1990 (Cont)

5.8L V-8 G FBC (2150A)* E and F Series Trucks/Vans EEC-IV

7.3L V-8 M Diesel

(8500 lb. GVW or less only)

7.5L V-8 G EFI

1991-1994

2.3L I-4 OHC A EFI, MFI Ranger EEC-IV

2.9L V-6 T EFI

3.0L V-6 U EFI, SEFI, SFI Aerostar, Ranger

4.0L V-6 X EFI, MFI Aerostar, Explorer, Ranger

4.9L I-6 Y, H EFI, MFI, SFI Bronco, E and F Series Trucks/

5.0L V-8 N EFI, MFI, SFI

Vans (8500 lb. GVW or less only)

5.8L V-8 H, R EFI, MFI, SFI

7.3L V-8 M Diesel E and F Series Trucks/Vans

7.3L V-8 K Turbo Diesel

(Excludes 1994 diesel models)

7.5L V-8 G EFI, MFI

1995

3.0L V-6 U SFI Aerostar (Excludes Explorer, EEC-IV

Ranger and Windstar)

4.0L V-6 X SFI

4.9L I-6 Y SFI E and F series Trucks and Vans

(Excludes Natural Gas equipped
vehicles)

5.0L V-8 N SFI Bronco, E and F series Trucks

and Vans

5.8L V-8 H, R MFI

7.5L V-8 G MFI E-350; F-250-350 (Excludes

California ); F-Super Duty
(Excludes Diesel)

NOTES

* Carburetor Model. Carburetor model numbers are usually stamped on top of the

carbure-tor, or on a metal tab attached to the carburetor. Consult your vehicle’s repair
manual for proper identification.

**VIN Number. The VIN number(s) used in this column identify the vehicle’s engine
type. This number is the 8th digit of the VIN (Vehicle Identification Number). Consult
your vehicle’s repair manual for details.

Application Table Definitions. EFI = Electronic Fuel Injection; FBC = Feedback
Carburetor; MFI = Multiport Fuel Injection; OHC = Overhead Cam; SC = Super
Charged; SEFI = Sequential Electronic Fuel Injection; SFI = Sequential Fuel Injection

1

General Information

PRELIMINARY VEHICLE DIAGNOSIS WORKSHEET

Chapter 1 8

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 form to help
you and/or your mechanic have a clear understanding of your vehicle's
problems.

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:

1

General Information

PRELIMINARY VEHICLE DIAGNOSIS WORKSHEET

9 Chapter 1

WHEN DID YOU FIRST NOTICE THE PROBLEM:

❑ Just Started
❑ Started Last Week
❑ Started 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
❑ Starts, but takes a long time

❑ No symptoms
❑ Right after starting
❑ When shifting into gear
❑ During steady-speed driving

❑ 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

1

General Information

PRELIMINARY VEHICLE DIAGNOSIS WORKSHEET

Chapter 1 10

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

❑ Short - 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 curvy 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 rubber

❑ 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

1

About Diagnostic Systems

WHAT ARE THE ADVANTAGES OF COMPUTER CONTROL SYSTEMS?

11 Chapter 2

WHAT ARE THE ADVANTAGES OF USING COMPUTER
CONTROL SYSTEMS ON VEHICLES?

Vehicle Computer Control Systems can perform millions of
calculations in one second, making them an ideal substitution
for the much slower mechanical engine controls. By switching
from mechanical engine controls to electronic engine controls,
vehicle manufacturers were able to control fuel delivery and
spark timing as well as other engine functions (some newer
Computer Control Systems also control transmission, brakes,
charging, body and suspension systems) more precisely. This
made it possible for vehicle manufacturers to comply with the
new, tougher emission and fuel efficiency standards mandated
by State and Federal Governments.

HOW DOES A COMPUTER SYSTEM WORK ON A
VEHICLE, AND WHAT IS IT’S MAIN PURPOSE?

The main purpose of the vehicle’s Computer Control System is
to provide maximum engine performance with the least
amount of air pollution and the best fuel efficiency possible.

The Computer Control System consists of the on-board
computer, and several related control devices (sensors,
switches, and actuators). 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. Some
manufacturers may still position it in the engine compartment.
The sensors, switches, and actuators are devices such as
oxygen sensors, coolant temperature sensors, throttle position
sensors, fuel injectors, etc., that are located throughout the
engine, and are connected by electrical wiring to the on-board
computer.

The on-board computer is the heart of the Computer Control
System. The computer contains several programs with pre­programmed reference values for air/fuel ratio, spark or
ignition timing, injector pulse width (how much fuel is injected
into the engine), engine speed, etc., for all possible driving
conditions (idle, low speed driving, high-speed driving, low
load, high load, etc.). The pre-programmed reference values
represent the ideal air/fuel mixture, spark timing,
transmission gear selection, etc., for any driving condition.
These values are programmed at the factory and are specific to
each vehicle model.

2

About Diagnostic Systems

HOW DOES A COMPUTER SYSTEM WORK ON A VEHICLE?

Chapter 2 12

The on-board computer receives information (inputs) from
sensors and switches located throughout the engine. These
devices monitor critical engine conditions (coolant
temperature, engine speed, engine load, throttle position,
air/fuel ratio etc.). The computer compares the actual values
received from these sensors with the reference values that are
programmed in it’s memory, and makes corrections as needed
so that the sensor values always match the pre-programmed
reference values for that particular driving condition.

Since 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 pre-programmed
reference values.

NOTE:

The computer does not make the adjustments or
corrections directly. It commands other devices such as the fuel
injectors, idle air control, EGR valve or Ignition Module to
perform these functions. These devices are called Actuators
because they initiate an action in response to the commands of
the computer.

How a Special Program in the Computer Detects and
Reports Problems in the System

•

Beginning in 1988 California’s Air Resources Board (CARB),
and later, the Federal Government's Environmental
Protection Agency (EPA), required vehicle manufacturers
to include a self diagnostic program capable of identifying
an emissions-related fault in a system in their On-board
Computers. The first generation of On-board
Diagnostics came to be known as OBD I.

NOTE:

Most manufacturers (including Ford) began
installing computers with On-Board Diagnostics on some
of their vehicles as early as 1981.

•

OBD I is a set of self-testing or self-diagnosing instructions
that are programmed into the vehicle’s on-board computer.

•

The program is specifically designed to detect failures in
the sensors, actuators, switches and wiring of the various
vehicle emissions-related systems (fuel injection system,
ignition system, EGR system, catalytic converter, etc.). If
the computer detects a failure in any one of these
components or systems, it alerts the driver by
illuminating a light on the dash (the light will illuminate
only if it is an emissions-related problem).

2

About Diagnostic Systems

HISTORY OF FORD’S EEC SYSTEMS

13 Chapter 2

•

The computer also assigns a numeric code (OBD I systems
utilized a 2 or 3 digit code) for each specific problem that it
detects, and stores these codes in it’s memory for later
retrieval. The codes can be retrieved from the computer’s
memory with the use of a device called a “Code Reader” or
a “Scan Tool”.

•

In addition to storing Diagnostic Trouble Codes for
detected problems, most Ford computer systems are also
designed to perform special Self Tests in real time, and to
send the test results to the Code Reader as two- or three­digit Diagnostic Trouble Codes.

NOTE:

With the exception of some 1994 and 1995 vehicles most
vehicles from about 1982 to 1995 are equipped with OBD I
systems.

HISTORY OF FORD’S ELECTRONIC ENGINE CONTROL
(EEC) SYSTEMS

1978: Ford Motor Company introduces its first “Electronic
Engine Control (EEC-I)” system. This system was very

limited in the control of engine functions and only controlled
ignition timing, EGR flow and the air pump's injection of air
into the exhaust.

1979: Ford introduces the EEC-II system. This system added
air/fuel ratio control (feedback carburetor), throttle kicker
(controls engine idle speed during start up and AC function)
and canister purge control to the ECC-I system.

1980: Ford introduces the EEC-III system. This system
included all the sensors used by the ECC-II system, with the
addition of a temperature Sensor. In 1981, the ECC-III system
was modified to include controls for the new Electronic Fuel
Injection systems. The EEC-III system was used on some
models of Ford vehicles until 1984.

1980: In addition to the EEC-III system, Ford introduced
another computer control system, called the “Microprocessor
Control Unit (MCU)”. This system was used on a limited
number of Ford vehicles up until 1991.

1983: Ford introduces the “Electronic Engine Control - IV
(EEC-IV)” system. This system is capable of controlling a

larger number of sensors, switches and actuators, and was
used on a greater number of Ford vehicles. The ECC-IV
system was used from 1983 to 1995.

2

About Diagnostic Systems

FORD COMPUTER SYSTEM OVERVIEW

Chapter 2 14

1994: Ford introduces the EEC-V system (OBD-II). This is a
highly sophisticated system that uses more special programs
to enhance the computer's capability to monitor, detect and
report failures, especially to the vehicle's emission system.
This system was introduced on a limited number of 1994 and
1995 vehicles. Starting in 1996, all Ford vehicles (cars and
light trucks) sold in the US are equipped with the EEC-V
system.

NOTE:

The Ford Digital Code Reader is compatible only with
the MCU and the EEC-IV Computer Control systems. The
EEC-I, EEC-II, EEC-III and the EEC-V (OBD-II) systems
require specialized equipment to diagnose computer problems
and/or retrieve fault codes and are not compatible with the
Ford Digital Code Reader.

FORD COMPUTER SYSTEM OVERVIEW

Ford vehicle's computers are factory-programmed with special
Self-Testing instructions that are specially designed to detect
any failures in the various systems that the vehicle's computer
monitors and controls. The computer monitors the vehicle’s
sensors (oxygen sensors, coolant temperature sensors, mass
airflow sensors, EGR valve, MAP sensors, etc.) and actuators
(fuel injectors, EGR system, idle air control, cooling fan, canister
purge solenoid, spark advance, etc.) for proper operation. All of
these devices are connected to the vehicle's computer by wires.

The sensors communicate with the computer by sending
voltage signals (inputs) that correspond with the vehicle's
current operating condition. If the voltage that the computer
receives from a particular sensor does not agree with the
voltage value that is programmed in its memory for that
particular driving condition. A Diagnostic Trouble Code is
generated that pertains to that particular circuit or system.

Actuators receive commands from the computer in the form of
voltage signals to perform a certain functions or adjustment.

Example: The computer might command a fuel injector to
increase the amount of fuel injected into the engine. After
the computer commands the fuel injector to inject more fuel
in to the engine, it then monitors the voltage signal from
that injector to ensure that the injector has responded. If
the fuel injector's voltage signal does not change, it
indicates that the fuel injector is not responding to the
computer’s command. The computer then determines that
there is a problem in the injector or injector circuit, and
generates a code related that particular problem. This code
is sent to the Code Reader during the Self Test procedure.

2

About Diagnostic Systems

FORD COMPUTER SYSTEM OVERVIEW

15 Chapter 2

IMPORTANT:

When the computer is in Self Test mode (is
testing the sensors or actuators for proper operation), it relies
on voltage signals that it sends to and/or receives from the
sensors or actuators to determine whether or not these
components are operating properly. The sensors and actuators
are all connected to the computer by wires. If any defects are
present in any part of the circuit that connects these devices to
the computer (such as defective connectors or wires, faulty
grounds, improper voltage, shorts etc.), the voltage signal that
the computer receives from these devices will be affected. The
computer has no way of determining if the improper voltage
signal is being caused by a defect in the circuit or by the sensors
or actuators themselves. Keep this in mind when servicing
Fault Codes, and do not replace any devices (sensors or
actuators) before checking the complete circuit (or circuits) that
are part of the device from which the code was generated.

2

About Diagnostic Systems

Chapter 2 16

2

BEFORE YOU BEGIN

•

Fix any known mechanical problems before performing
any test.

Make a thorough check before starting any test procedure.
Loose or damaged hoses, wiring or electrical connectors are
often responsible for poor engine performance, and in some
cases they may cause a "false" fault code.

Please read your vehicle's service manual for proper
connection of vacuum hoses, electrical wiring and wiring
harness connectors. Check the following areas:

a. All fluid levels - check the oil, power steering, trans-

mission (if applicable), coolant and other engine fluids.

b. Air cleaner and ducts - check for holes, rips, excessive

dirt in filter, and for disconnected ducts. You may wish to
check your owner's manual to determine when you should
change the air filter.

c. Belts - check for ripped, torn, brittle, loose or missing belts.
d. Mechanical linkage associated with sensors - Refer

to your vehicle's service manual for locations.

e. Rubber (vacuum/fuel) and steel hoses - check for leaks,

cracks, blockage or other damage; check for proper routing.

f. Spark plugs and wires - check for damaged, loose,

disconnected or missing spark plug wires.

g. Battery terminals - make sure battery terminals are

clean and tight; check for corrosion or broken connections.
Verify proper battery and charging system voltage.

h. Electrical connectors and wiring - make sure wire

insulation is in good condition and there are no exposed
wires. Make sure all cables are connected securely.

i. V

erify that the engine is mechanically sound. If necessary,
perform a compression check, engine vacuum check,
timing check (if applicable), etc.

Preparing The Code Reader For Use

Installing the Battery

■ 2 - "AA" batteries are required to perform tests.

■ Batteries sold separately.

a. Remove the battery compartment cover from the back of

the Code Reader.

About the Ford Code Reader

BEFORE YOU BEGIN

17 Chapter 3

3

About the Ford Code Reader

TEST CONNECTORS

Chapter 3 18

b. Match battery terminals with battery connector contacts.
c. Place batteries into battery compartment.
d. Reinstall battery compartment cover.

TEST CONNECTORS

•

The gateway to your vehicle's onboard computer.

Ford equips its vehicles with special Test Connectors that
make it possible to connect specialized testing equipment that
communicates with the vehicle's onboard computer.

Ford's vehicle test connectors are usually dark in color
(BLACK or GREY) and found under the hood. Sometimes they
have a plastic cover over them or are labeled EEC Test. The
connectors can be found in the following general locations in
the engine compartment:

•

Near the front corner (right or left).

•

Near the fender well (right or left).

•

Near the fire wall (right or left).

CONNECTING THE FORD CODE READER TO THE
VEHICLE’S TEST CONNECTOR(S)

NOTE:

The Code Reader is designed to match the computer's
test connector. When properly connected, the test connector
should match the pre-molded guides around the Code Reader
pins (as shown on next page).

Forcing the test connector onto the Code Reader improperly
may result in damage to the Code Reader and possible damage
to the vehicle's computer system.

3

6-PIN

SINGLE

PIN

EEC-IV TEST CONNECTOR MCU TEST CONNECTOR

6-PIN

About the Ford Code Reader

FUNCTIONS OF THE FORD CODE READER

19 Chapter 3

■ For the EEC-IV Computer System (most vehicles built

after 1984) connect the Code Reader to BOTH.

1. large, six pin female con-

nector with molded housing

2. small, single pin female

connector

NOTE:

1988 and newer vehicles
may have more than one similar
connector for other systems (i.e.
Anti-Lock Brakes), only the
connector with an extra single
pin is the correct test connector
for computer service codes use. If
you have any questions about the
correct connector please refer to
your vehicle's service manual for
detailed information.

■ For the MCU System (most

vehicles built between 1981-

1983) connect the Code
Reader to the six pin female
connector only.

Optional Extension Cable

For one person operation, a 6'
optional extension cable for test
connection is available through your
local store or service department.
The extension cable allows you to do
all the code reading without the help
of another person.

FUNCTIONS OF THE FORD CODE READER

The Ford Digital Code Reader is a diagnostic tool that is
specially designed to connect to the vehicle's test Connector(s)
to communicate with the vehicle's computer.

The Code Reader does not generate codes. The Code Reader
serves as a “key” that links to, and opens communication with
the vehicle's computer to prompt the computer to perform Self
Tests, and to receive test results or retrieve codes.

3

MCU

TEST

CONNECTOR

CODE

READER

EEC-IV
TEST
CONNECTOR

CODE
READER

FORD

FORD

About the Ford Code Reader

FUNCTIONS OF THE FORD CODE READER

Chapter 3 20

The vehicle's computer generates and assigns fault codes
whenever it detects a problem in any of the various systems
that it monitors and/or controls. Once the Code Reader is
connected to the vehicle's Test Connector(s), the user can
signal the computer to perform the Self-Tests (by pressing the
TEST/HOLD button). The computer then starts performing a
Self Test of all the components and/or circuits it controls. The
results of the tests are sent to the code reader (as numerical
codes) to help the repairperson pinpoint a particular problem
in any of the computer control systems.

This Code Reader is designed to retrieve Diagnostic Trouble
Codes from Ford EEC-IV and MCU systems only.

Code Reader Controls and Indicators

1. Code Reader Connector - Connects to the vehicle's six-

pin Test Connector (the six-pin test connector is used on
both MCU and ECC-IV systems).

2. Code Reader Connector - Connects to the vehicle's

single-pin Test Connector. (the single-pin Test Connector
is used on EEC-IV systems only; MCU systems are not
equipped with single pin test connectors).

3. LCD Display - Displays test results, Diagnostic Trouble

Codes and Code Reader functions.

4. ON/OFF Button - Turns the code reader On and Off.

5. TEST/HOLD Button: Toggles between TEST and HOLD

functions.

3

2

MEMORY ON / OFF

6

TEST / HOLD

FORD LINCOLN MERCURY

Domestic vehicles 1981 to 1995

1

3

4

5

About the Ford Code Reader

FUNCTIONS OF THE FORD CODE READER

21 Chapter 3

6. MEMORY Button - When pressed, displays on demand,

one at a time, the retrieved Diagnostic Trouble Codes that
are saved in the Code Reader's memory (the Code Reader
memory has the capacity to store up to 12 retrieved
numeric Diagnostic Trouble Codes).

Display Functions

1. CYL Icon: When visible, this icon indicates that the

number shown on the the Code Reader's display is a
cylinder identification code. Cylinder codes identify the
number of cylinders of the engine under test. Cylinder
identification is only displayed when performing a KOER
Self Test.

2. BATTERY Icon: When visible, this icon indicates that

the Code Reader's internal batteries are low. Batteries
should be replaced before performing any tests.

3. O, R, and C Icons: These icons indicate the type of test

being performed, and indicate if the code being received is
a KOEO, KOER or CM code:

O = Key On Engine Off (KOEO) Test/code
R = Key On Engine Running (KOER) Test/code
C = Continuos Memory (CM) code

These icons also identify the "code type" when viewing
Diagnostic Trouble Codes that are saved in the Code
Reader's memory.

3

12 3

O

C

CYL

6

R

4

5

About the Ford Code Reader

FUNCTIONS OF THE FORD CODE READER

Chapter 3 22

4. "FLASHING" SQUARE Icon: This icon flashes when the

Code Reader receives Diagnostic Trouble Codes from the
vehicle's computer. The icon flashes each time a code is
received; the code is then shown on the Code Reader’s
display.

5. LINK Icon: When visible, this icon indicates that the

Code Reader is linked to the vehicle's computer, and the
computer is in test mode.

6. Diagnostic Trouble Code Display Area: Displays the

Diagnostic Trouble Code number. Each fault is assigned a
code number that is specific to that fault.

3

Retrieving Codes

OVERVIEW OF FAULT CODES

23 Chapter 4

OVERVIEW OF FAULT CODES

IMPORTANT:

Retrieving and utilizing Diagnostic Trouble
Codes (DTC's) for troubleshooting vehicle operation problems is
only one part of an overall diagnostic strategy. Never replace
a part based only on the Diagnostic Trouble Code Definition.
Always consult the vehicle's service manual for more detailed
testing instructions. Each DTC has a set of testing procedures,
instructions and flow charts that must be followed to confirm
the exact location of the problem. This type of information is
found in the vehicle's service manual.

a. Fault Codes are called "Diagnostic Trouble Codes" (DTCs),

"Trouble Codes", “Fault Codes” or "Service Codes" (these
terms are used interchangeably throughout this manual).
These numeric codes are used to identify a problem in any
of the systems that are monitored by the vehicle's on­board computer.

b. Each Fault Code is assigned a message that identifies the

circuit, component or system area where the problem was
detected.

c. Ford Diagnostic Trouble Codes are composed of two- or

three-digit numbers.

■ Most early model Ford vehicles (up to 1991) use a two-

digit code system.

■ Most late model Ford vehicles (1992 to 1995) use a

three-digit code system.

The computer records codes for three types of
conditions:

1. It records Fault Codes for problems that are present at the

time the Self-Tests are performed (the Code Reader is
used to place the vehicle's computer in Self-Test Mode; the
procedures are described in detail later in this manual).
These types of codes are usually called "Hard Codes".
Hard Codes will make the check engine light or
Malfunction Indicator Lamp (MIL), if equipped, on the
dash to come on and stay on solid.

2. It records and saves Fault Codes for "Intermittent

Problems" (not applicable to MCU systems). These
problems come and go intermittently. Intermittent Fault
Codes may cause the Check Engine/Malfunction Indicator
Lamp (MIL) light to flicker on dash.

4

Retrieving Codes

OVERVIEW OF FORD CODE RETRIEVAL PROCESS

Chapter 4 24

3. It records and retains in its memory (not applicable to

MCU systems) a record of faults that occurred in the past
but are no longer present. The vehicle's computer keeps
these Fault Codes in its memory for a specific period of
time (40 Warm Up cycles* for most fault Codes, 80 Warm
up cycles for others) even if the problems that caused
these codes to be set in the first place are no longer
present.

*Warm-up Cycle - A Warm-up Cycle is defined as vehicle
operation (after an engine off period) where the engine
temperature rises at least 40°F (22°C) from the
temperature present when the vehicle was first started,
and the engine temperature reaches at least 160°F (70°C).

NOTE:

The Code Reader does not generate codes. The Code
Reader serves as a “key” that links to, and opens
communication with the vehicle's computer to prompt the
computer to perform Self Tests, and to receive test results or
retrieve codes.

OVERVIEW OF FORD CODE RETRIEVAL PROCESS

Ford’s computer self-diagnostic system is divided into three
main sections: 1. "Key On Engine Off" (KOEO) Self Test, 2.
"Continuous Memory" (CM) Self-Test and 3. "Key On Engine
Running" (KOER) Self Test. These Self-Tests are specially
designed to monitor and/or test the various components and
circuits that are controlled by the vehicle's computer, and to
save and/or transmit diagnostic test results to the Code
Reader in the form of numerical fault codes.

•

The “Continuous Memory” Self Test is designed to run
continuously whenever the vehicle is in normal operation.
If a fault is detected by the “Continuous Memory” Self
Test, a fault code is saved in the vehicle's computer
memory for later retrieval.

NOTE:

Continuous Memory codes only apply to EEC-IV

systems and are retrieved during the KOEO Self Test.

•

Ford designed its On-Board Diagnostic Self Tests in such
a way that in order to properly diagnose a problem, you
must performed all

the Self Tests, in the proper sequence.
As described above, some tests are designed to detect
problems only when the vehicle is in normal operation,
some tests are designed to activate components and detect
problems only with the Key On and Engine Off, and other

4

Retrieving Codes

KOEO TEST PROCEDURES (EEC-IV SYSTEMS)

25 Chapter 4

tests are designed to activate components and test their
operation only with the Key On and Engine Running. Do
not take short cuts. If you fail to perform a test, or you
perform a test out of sequence, you might miss a problem
that is only detected during that particular test procedure.

To properly receive Diagnostic Trouble Codes from the
Ford computer control system, perform the Self Tests in
the following order:

1. Key On Engine Off (KOEO) Self Test

2. Ignition Timing Check (vehicle Ignition Timing System

must be working properly before the KOER Self Test can
be performed)

3. Key On Engine Running (KOER) Self Test

IMPORTANT:

•

To retrieve Diagnostic Trouble Codes from EEC-IV
Systems proceed to the next section below.

•

To retrieve Diagnostic Trouble Codes from MCU systems
proceed to page 66.

KEY ON ENGINE OFF (KOEO) TEST PROCEDURES
(EEC-IV SYSTEMS)

NOTE:

During the KOEO Self Tests two groups of codes will be

sent to the Code Reader by the vehicle’s computer.

•

The first groups of codes sent to the Code Reader are called
"KOEO Self Test codes",

•

followed by the second group called "Continuous Memory
Codes".

NOTE:

Before the computer sends the second group of codes to
the Code Reader, it first sends a “separator code” (code 10) to
separate the first group of codes from the second group.

•

Always observe safety precautions before and during
testing process.

•

ALWAYS check Code Reader battery before retrieving
fault codes.

•

Fix any known mechanical problems before this test.

1. Warm-up engine to normal operating temperature before

performing this test.

2. Turn ignition off.

4

Retrieving Codes

KOEO TEST PROCEDURES (EEC-IV SYSTEMS)

Chapter 4 26

3. With Code Reader off, connect to the vehicle's test

connectors (see page 18 for test connector location).

■ Both the large and small connectors must be

connected.

4. If your vehicle is equipped with one of the following

configurations, perform the added procedures as described
below.

■ For 4.9L engines with standard transmission: press

and hold the clutch until all Codes are sent (Steps 4 to

10).

■ For 7.3L diesel engines: press and hold accelerator

until all codes are sent (Step 4 to 10).

■ For 2.3L turbo engines with octane switch: put switch

in premium position.

NOTE:

Do not press throttle or brake, or move steering

wheel, during this test unless instructed.

5. Turn ignition on. DO NOT START THE ENGINE.

WARNING:

Keep away from any potentially moving parts.

6. Press and release the ON/OFF

button to turn the Code Reader
"ON".

■ Three zeros should be

visible on the Code Reader
display at this time.

7. Press and release the

TEST/HOLD button to put the
Code Reader in Test Mode.

■ When the code reader is put in test mode it signals

the vehicle's computer to start performing the Self­Test. The display will show a "Triangle" icon on the
lower right hand corner of the display to indicate that
the Code Reader is linked to the vehicle's computer
and is in test mode.

NOTE:

As soon as the TEST/HOLD button is pressed
the vehicle's computer enters the Self Test mode.
Clicking sounds will be heard coming from the engine.
This is normal. It indicates that the vehicle's computer
is activating relays, solenoids, and other components
to check their operation.

4