Service Manual - Off-Road - Toyota Tech - Diagnostic Trouble Codes.pdf - Toyota - danio199303

Off-Road.Com - Toyota Tech - Diagnostic Trouble Codes

Diagnositc Trouble Codes and Possible Causes

By Jim Brink

(toytech@off-road.com)

All Toyota vehicles with electronic fuel injection utilize the Toyota EFI

or TCCS engine management system. This system incorporates many

features to enhance performance, emissions, and drivability. One feature

is the Self Diagnostic System. The self diagnostic system monitors

engine operations and when a particular sensor or input varies out of

specified operating parmeters, the " Check Engine" will be illuminated.

The check engine lamp alerts the driver or technician that a problem

exists in the EFI/TCCS ECU or E ngine C ontrol U nit or "computer."

When the check engine light is illuminated, it is indicating that a

problem in the engine management system has been detected. At this

time, a "code" may be stored in the ECU which pinpoints a possible

component in the EFI/TCCS system. By checking the trouble codes, a

possible problem could be narrowed down to a number of causes. While

not an exact diagnostic tool, the check engine light and self-diagnostic

system can get the individual working on his/her truck close to a possible

fault, and, hopefully, to a successful repair.

Listed below are one and two digit trouble codes for the EFI/TCCS

systems and possible causes. As mentioned above, this is not an exact

science. Many other component failures can cause similar symptoms that

can "mask" the actual cause. EFI/TCCS computer interrogation is one of

the last steps to engine diagnostics. A thourough inspection of the

simple items should be done prior to any computer-related repairs.

Sometimes it's the simple things that will get ya'. In addition, use caution

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Off-Road.Com - Toyota Tech - Diagnostic Trouble Codes

when working on the electrical system of your vehicle. Not only is the

electrical system delicate to water, static electricity, and outright physical

abuse, the ignition system puts out high voltage as well and you can be

serioulsy injured if you do not exercise basic safety.

READING THE TROUBLE CODES

Reading the diagnostic trouble codes is very easy. You will need a paper

clip to short the check connectors of the diagnostic connector. The

diagnostic connector comes in two types. The early system is located on

the inner-left fender well and is a round, green connector, usually located

near the air cleaner. Simply jump the two terminals in this connector

with the ignition switch in the "ON" position and the engine off. Later

models, '87 and newer use a multiple terminal "DIAGNOSTIC"

connector which is a small, rectangular-shaped grey "box", usually

located near the right fender in the enigne compartment. To get codes out

of this type of connector, jump the "TE1" and "E1" teminals. Finding

these terminals is easy as the inside cover of the diagnostic connector

contains a schematic of the connector pinouts. If the underhood emission

decal (VECI) is still intact on your vehicle, the proper pins for this are

outlined there as well.

The trouble codes will appear as flashes of the check engine lamp. Be

sure the ignition key is on, the engine off, and your foot off of the

accelerator when reading the codes. Two different codes may appear:

One-digit and two digit. One digit codes have an approximate 4.5 second

delay between flashes with the check engine light illuminating for about

a half of a second. Mulitiple codes have a 2.5 second delay between

them. For example a code two flashes the check engine lamp two times

in a little over one second: I I. If two codes are stored, such as a code

two and a code four, the lamp may flash as such: ....I I....I I I I. Crude

examples but you get the idea. Two digit codes are similar but will flash

the lamp with the first number first and the second number last. An

example of a code twleve is I ....II and a code twenty four is I I..IIII.

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Off-Road.Com - Toyota Tech - Diagnostic Trouble Codes

Later-model EFI/TCCS Diagnositc Connector

(Photo courtesey of Chris Geiger)

TROUBLE CODES AND POSSIBLE CAUSES

ONE-DIGIT TWO-DIGIT POSSIBLE CAUSE OF CODE/SYMPTOM

NONE

SYSTEM NORMAL

LOSS OF POWER SUPPLY TO ECU

--IGNITION SWITCH/CIRCUIT

--MAIN RELAY/CIRCUIT

--ECU

RPM SIGNAL-NO SIGNAL TO ECU FROM DISTRIBUTOR ("Ne"

OR "G") AFTER ENGINE HAS BEEN CRANKED

--DISTRIBUTOR/CIRCUIT

--STARTERSIGNAL CIRCUIT

--IGNITER/IGNITER CIRCUIT

--ECU

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Off-Road.Com - Toyota Tech - Diagnostic Trouble Codes

SAME AS ABOVE BUT AFTER ENGINE HAS RUN AT 1,000-1,500

RPM

--DISTRIBUTOR/DISTRIBUTOR CIRCUIT

--ECU

IGNITION SIGNAL--NO "IGF" SIGNAL TO ECU

--IGNITER/IGNITER CIRCUIT

--IGNITER AND IGNITION COIL/CIRCUIT

--ECU

OXYGEN SENSOR SIGNAL/OXYGEN SENSOR HEATER

SIGNAL

OPEN OR SHORT IN OXYGEN SENSOR OR OXYGEN SENSOR

SIGNAL

WATER TEMPERATURE SENSOR SIGNAL--OPEN OR SHORT

IN WATER TEMP. SENSOR SIGNAL

--WATER TEMPERATURE SENSOR CIRCUIT

--WATER TEMPERATURE SENSOR

--ECU

INTAKE AIR TEMPERATURE SENSOR SIGNAL--OPEN OR

SHORT IN INTAKE AIR TEMP. SIGNAL

--INTAKE AIR TEMPERATURE CIRCUIT

--INTAKE AIR TEMPERATURE SENSOR

--ECU

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Off-Road.Com - Toyota Tech - Diagnostic Trouble Codes

AIR/FUEL RATIO LEAN INDICATOR--LEAN SIGNAL SENT TO

ECU FROM O2 SENSOR

--INJECTOR FAULT(S)

--FUEL PRESSURE

--OXYGEN SENSOR

--AIRFLOW METER OR MAP SENSOR

--IGNITION

--ECU

AIR/FUEL RATIO RICH INDICATOR

--SAME AS ABOVE

--COLD START INJECTOR

SUB-OXYGEN SENSOR CIRCUIT OR SUB-OXYGEN SENSOR

HEATER CIRCUIT

--SUB OXYGEN SENSOR/HEATER/CIRCUIT

--ECU

No.2 OXYGEN SENSOR/OXYGEN SENSOR HEATER

--SAME AS CODE 21

MANIFOLD AND/OR AIRFLOW METER SENSOR SIGNAL

CIRCUIT

--AIRFLOW METER/CIRCUIT

--MANIFOLD PRESSURE SENSOR/CIRCUIT

--ECU

AIRFLOW METER SIGNAL (VANE-TYPE)

--AIRFLOW METER./CIRCUIT

--ECU

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Service Manual - Off-Road - Toyota Tech - Diagnostic Trouble Codes.pdf

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