For Toyota's with electronic fuel injection utilizing the Toyota EFI or TCCS engine management system.

     

    Toyota's with the electronic fuel injection utilize the Toyota EFI or TCCS engine management system.  This system helps to enhance the performance, emissions, and drivability of the vehicle.  The Self-Diagnostic System, which monitors engine operations, is just one of the features of this system.  The Check Engine light will appear when a particular sensor or input varies out of the specified operation parameters.
 
     The check engine light alerts the user that there is a possible problem in the EFI / TCCS Engine Control Unit.  This is an indication of a problem in the engine management system.  A code that pinpoints a possible component in the EFI / TCCS system may be stored in the ECU at this time.  The problem can be narrowed down to a number of possible causes just by checking the trouble codes at this time.  The self-diagnostic system allows the user to zero in on the possible fault.
 
     The chart on the BOTTOM of this page contains 1 and 2 digit trouble codes that will help to diagnose problems in the EFI / TCCS system.  The chart also contains possible causes of the problem.  Keep in mind this is a tool to help narrow down the problem and may not be exact.  Other components failures have been known to cause similar symptoms that can hide the actual fault.
 
     Be sure to do a complete inspection before you do any repairs on the computer of the vehicle.  The last step to an engine diagnose should always be a computer interrogation.
    
     Remember to be cautious with the electrical system within the vehicle.  Serious injury can occur if the user or technician is now careful.  the electrical system can be damaged if not careful; water and static electricity can easily cause damage.  Also keep in mind that the ignition system does put out high voltage.  Always put your safety first when dealing with these components of your vehicle.
 
     The diagnostic trouble codes are easy to read.  All you need is a simple paper clip to short the check connectors of the diagnostic connector.  There are two different types of diagnostic connectors.  For those of you who own an early model vehicle, check on the inner-left fender well for a round green or yellow connector close to the air cleaner.  With the ignition key on, but the motor off, jump the two terminals in the connector.  On the later models, 87 and newer, there is a multiple terminal "Diagnostic" connector which is located in the engine compartment on the right fender.  Look for a small rectangular shaped gray box.  In order to get the codes from this connector you need to jump the "TE1" and "E1" terminals.  To find the terminals, look at the inside of the diagnostic connector.  Here you will find a schematic, which labels the connector pinouts.  There is also a (VECI) emissions decal located under the hood, which also outlines the terminals.
 
     The trouble codes will appear as flashes of the check engine light.  When reading the codes, make sure your foot is OFF the accelerator, the ignition key ON and the engine is OFF.   There are two different codes that will appear, one digit and two digit.  The one digit codes have and approximate 4.5 sec. delay between flashes with the check engine light illuminating for around a half second.
 
     On the two digit codes you will have a 2.5 sec. delay between them.  Here are some example codes to follow.  A code two flashes the check engine light two times in little over one second; I I.  When multiple codes are stored, like a code 2 and code 4, the light will flash the following; ....I I....I I I I.  Two digit codes are real similar, but will flash the light with the first number first then the second dumber last.  For example, a code 12 will flash; I....I I.  A code 24 is; I I....I I I I.  The examples are a little crude but you get the idea.  (In these examples, the ..I.. represents the check engine flashing once.)
 
     An ECU failure is not common, although many possible faults might seem to point to the EFI system.  Only if all diagnoses points to a faulty ECU should it be replaced.  Typically EFI problems result from poor grounds, shorted wiring and bad connections at sensors.
 
     For more comprehensive diagnostic information and electrical wiring diagrams, carefully consult your factory repair manual.

In case of not having a working check engine light, you can carefully insert a paper clip on the "W' Pin and use a grounded test light, in order to see the check engine light flashes.

Early 22RE engines:

CODE

DESCRIPTION / PROBABLE CAUSE(S)

1

Normal operation (no code stored)

2

Open or shorted Air Flow Meter (AFM) circuit
- Defective AFM
- Defective Electronic Control Unit (ECU)

3

No signal from igniter 4 times in succession
- Defective Igniter
- Defective Main Relay circuit
- Defective ECU

4

Open or shorted Water Thermo Sensor (THW) circuit
- Defective THW
- Defective ECU

5

Open or shorted Oxygen Sensor (O2) circuit
- Lean or rich indication (with injectors full rich or full lean)
- Defective O2 sensor
- Defective ECU

6

No engine revolution sensor (Ne) signal to ECU
- Ne being over 1000 RPM in spite of no Ne signal to ECU
- Defective Igniter circuit
- Defective Igniter
- Defective distributor
- Defective ECU

7

Open or shorted Throttle Position Sensor (TPS) circuit
- Defective TPS
- Defective ECU

8

Open or shorter Air Thermo Sensor circuit
- Defective intake air thermo sensor circuit (see AFM)
- Defective ECU

9

not used?

10

No starter switch signal for ECU w/ vehicle speed = 0 and engine RPM > 800
- Defective Vehicle Speed Sensor (VSS)
- Defective main relay circuit
- Defective igniter switch to starter circuit
- Defective ECU

11

Short circuit in Check Connector T with A/C switch ON or TPS - IDL point OFF
- Defective A/C switch
- Defective TPS circuit
- Defective TPS
- Defective ECU

12

Knock control Sensor (KS) signal has not reached judgment level in succession
- Defective KS circuit
- Defective KS
- Defective ECU

13

Knock CPU (Sensor?) faulty

 

Some possible causes of the above trouble codes:

  • Codes 3 and 6 point to the coil and igniter, try a new one.
    • Another symptom is an erratic factory tachometer, as the tach. signal comes from the igniter circuit.
  • Any of the TPS codes; test out the Throttle Position Sensor both at the sensor and at the ECU connector,
    • Also make sure the TPS connector is tight.
  • Any of the AFM codes; test out the Air Flow Meter both at the sensor and at the ECU connector,
    • Also make sure the AFM connector is tight.
  • Any of the Knock Sensor codes; check the connector and wiring at the Knock Sensor, it is a shielded wire and is somewhat delicate.

Later 22RE engines:

ONE-DIGIT

TWO-DIGIT

POSSIBLE CAUSE OF CODE/SYMPTOM

1

NONE

SYSTEM NORMAL

--

11

LOSS OF POWER SUPPLY TO ECU
--IGNITION SWITCH/CIRCUIT
--MAIN RELAY/CIRCUIT
--ECU

6

12

RPM SIGNAL-NO SIGNAL TO ECU FROM DISTRIBUTOR ("Ne" OR "G") AFTER ENGINE HAS BEEN CRANKED
--DISTRIBUTOR/CIRCUIT
--STARTER SIGNAL CIRCUIT
--IGNITER/IGNITER CIRCUIT
--ECU

--

13

SAME AS ABOVE BUT AFTER ENGINE HAS RUN AT 1,000-1,500 RPM
--DISTRIBUTOR/DISTRIBUTOR CIRCUIT
--ECU

3

14

IGNITION SIGNAL--NO "IGF" SIGNAL TO ECU
--IGNITER/IGNITER CIRCUIT
--IGNITER AND IGNITION COIL/CIRCUIT
--ECU

5

21

OXYGEN SENSOR SIGNAL/OXYGEN SENSOR HEATER SIGNAL
OPEN OR SHORT IN OXYGEN SENSOR OR OXYGEN SENSOR SIGNAL

4

22

WATER TEMPERATURE SENSOR SIGNAL--OPEN OR SHORT IN WATER TEMP. SENSOR SIGNAL
--WATER TEMPERATURE SENSOR CIRCUIT
--WATER TEMPERATURE SENSOR
--ECU

8

24

INTAKE AIR TEMPERATURE SENSOR SIGNAL--OPEN OR SHORT IN INTAKE AIR TEMP. SIGNAL
--INTAKE AIR TEMPERATURE CIRCUIT
--INTAKE AIR TEMPERATURE SENSOR
--ECU

--

25

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

--

26

AIR/FUEL RATIO RICH INDICATOR
--SAME AS ABOVE
--COLD START INJECTOR

--

27

SUB-OXYGEN SENSOR CIRCUIT OR SUB-OXYGEN SENSOR HEATER CIRCUIT
--SUB OXYGEN SENSOR/HEATER/CIRCUIT
--ECU

--

28

No.2 OXYGEN SENSOR/OXYGEN SENSOR HEATER
--SAME AS CODE 21

2

31

MANIFOLD AND/OR AIRFLOW METER SENSOR SIGNAL CIRCUIT
--AIRFLOW METER/CIRCUIT
--MANIFOLD PRESSURE SENSOR/CIRCUIT
--ECU

--

32

AIRFLOW METER SIGNAL (VANE-TYPE)
--AIRFLOW METER./CIRCUIT
--ECU

14

34

TURBOCHARGER PRESSURE--ABNORMAL TURBOCHARGER PRESSURE
--TURBO CHARGER
--AIRFLOW METER/MANIFOLD/TURBOCHARGER PRESSURE SENSOR
--INTERCOOLER SYSTEM
--ECU

--

35

TURBOCHARGER PRESSURE SENSOR SIGNAL
--TURBOCHARGER PRESSURE SENSOR
--ECU

7

41

THROTTLE POSITION SENSOR SIGNAL--OPEN OR SHORT IN TPS SIGNAL
--TPS SENSOR
--TPS SIGNAL/CIRCUIT
--ECU

9

42

VEHICLE SPEED SENSOR SIGNAL CIRCUIT--NO SPD. SIGNAL FOR SEVERAL SECONDS
WHILE VEHICLE IS OPERATED UNDER HEAVY LOAD (TPS/MAP/AIR FLOW INPUTS)
--SPEED SENSOR/CIRCUIT
--ECU

10

43

STARTER SIGNAL--NO "STA" SIGNAL TO ECU UNTIL ENGINE SPEED EXCEEDS 800RPM
--IGNITION SWITCH/CIRCUIT
--ECU

11

51

SWITCH SIGNALS
IDL (tps) CONTACTS OFF, NEUTRAL START SWITCH OFF, A/C SWITCH "ON" SIGNAL TO ECU
WITH DIAGNOSTIC CHECK CONNECTOR SHORTED
--A/C SWITCH/CIRCUIT
--A/C AMPLIFIER
--TPS/CIRCUIT
--NEUTRAL START SWITCH/CIRCUIT
--ECU

12

52

KNOCK SENSOR SIGNAL--OPEN OR SHORT IN KNOCK SENSOR SIGNAL
--KNOCK SENSOR/CIRCUIT
ECU

13

53

KNOCK CONTROL SIGNAL IN ECU
--ECU

--

71

EGR VALVE MALFUNCTION--EXHAUST GAS TEMPERATURE BELOW SPEC. FOR EGR CONTROL
--EGR SYSTEM
--EGR GAS TEMPERATURE SENSOR/CIRCUIT

- -

72

AIR CONDITIONER COMPRESSOR RELAY/RELAY SIGNAL
--A/C COMPRESSOR RELAY/CIRCUIT
--ECU

 

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