OBD1 system trouble code gathering is a proprietary process to each manufacturer, below is the method on how to retrieve trouble codes for Toyota models before 1995, we also feature the code definition table as well.
Locate the diagnostic connector under the hood near passengers fender, or under the dash on the driver’s side, it will have a small plastic cover over the connector which is about 1 inch by 3 inches.
Turn the ignition key to the on position without turning starting the engine, observe the check engine light and count the number of times it blinks which will be the first digit of the two digit trouble code. 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 on constantly, to restart code gathering, turn the ignition key to the off position, wait three minutes and turn the ignition key back on again.
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.
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
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