Toyota is like most ODB1 systems, using the check engine light to blink out the trouble codes once a problem has occurred. If a check engine light is detected while driving the computer system has stored a trouble code for retrieval. Diagnostic trouble codes are used to help guide you to the system that has malfunctioned. To gather trouble codes locate the diagnostic connector under the hood near either fender or under the dash on the driver’s side. By using a jumper wire connect the TE1 and T1 terminals (For Tercel and MR2 use the T and E1 terminals). Turn the ignition key to the "on" position and observer the check engine light, then count the number of times it blinks this will be the first digit of the trouble code. 

Next, the check engine light will pause shortly followed by the second digit of the trouble code. For example if the check engine light blinks once and pauses followed by six blinks the trouble code number would be 16. If no code is present the check engine light will stay one constantly. To restart code gathering turn the ignition key to the "off" position, wait three minutes and turn the ignition key back "on" again without starting the engine. Remove the jumper wire once code gathering is complete. To clear code after the repairs have been made remove the negative battery cable for one minute and reconnect.

Toyota Diagnostic Connector

Toyota Code Definition Table

Code 11 Momentary interruption in power supply to ECU (electronic control unit or computer) up to 1991

Code 12 Engine revolution signal missing Code 13 Rpm signal to ecu missing above 1000 rpm

Code 14 Igniter signal to ecu missing

Code 16 A/T control signal missing from ecu

Code 21 Main oxygen sensor signal fault

Code 22 Water temperature sensor circuit fault

Code 23 and 24 Intake air temperature signal fault

Code 25 Air/fuel ratio LEAN

Code 26 Air/fuel ratio RICH

Code 27 Sub-oxygen sensor signal or heater circuit fault

Code 28 No. 2 oxygen sensor/heater signal fault

Code 31 and 32 Air flow meter circuit or Vacuum sensor signal fault Code 34 and 36 Turbo-charging pressure signal fault

Code 35 Altitude compensation sensor signal fault

Code 41 Throttle position circuit fault

Code 42 Vehicle speed sensor circuit

Code 43 No starter signal to the ecu

Code 51 AC signal on; DL contact off (in transmission shifter with diagnostic connector jumped)

Code 52, 53 and 55 Knock sensor fault Code 71 EGR system malfunction

Code 72 Fuel cut solenoid signal fault

Code 78 Fuel pump control signal fault

Code 81, 83, 84 and 85 TCM communication fault

If further assistance is needed, our certified car repair technicians are ready to answer your car questions. Also, gain manufacturer specific instructions and information by clicking - Auto Repair Manual

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