Audi OBD1 1991-1996 Idiot Light Diagnostic Guide without OBD Scanner 1

Audi OBD1 Idiot Light Diagnostic Guide without OBD Scanner

Audi OBD1 1991-1996 Idiot Light Diagnostic Guide without OBD Scanner idiot

General information

  • Trouble codes are displayed by using an LED connected to the data link connector (DLC).
  • The ECM fault memory can also be checked and erased using diagnostic equipment connected to the data link
    connector (DLC).
  • Self-diagnosis using flash type trouble codes may not display all available diagnostic information.
  • Carry out road test for 10 minutes.

Accessing

  • Ensure ignition switched OFF.
  • Bridge black data link connector (DLC) terminal 1 Fig. 1 [A] and brown or white data link connector (DLC) terminal 1 Fig.
  • 1 [B] with a switched lead – contacts normally open.
  • Connect LED test lamp between black data link connector (DLC) terminal 2 Fig. 1 [A] and ECM terminal 33.
  • 80: ECM located behind the passenger’s glovebox.
  • 100: ECM located in the plenum chamber.

NOTE: DO NOT disconnect ECM multi-plug as this will erase fault memory.

  • Start engine. Allow to idle.

NOTE: If engine does not start: Crank engine for 6 seconds. Leave ignition switched ON.

  • Operate switch for 4 seconds.
  • Release switch. Check that LED flashes.
  • Count LED flashes. Note trouble code.
  • Each trouble code consists of four groups of one to four flashes.
  • A 2,5 second pause separates each trouble code group Fig. 2 [A].
  • Repeat switch operation. Note trouble codes. Compare with trouble code table.
  • End of test sequence indicated by trouble code 0000 (long flashes).
  • Switch ignition OFF. Rectify faults as necessary.

Erasing Codes

Method 1

  • Ensure ignition switched OFF.
  • Bridge black data link connector (DLC) terminal 1 Fig. 1 [A] and brown or white data link connector (DLC) terminal 1 Fig. 1 [B] with a switched lead – contacts normally open.
  • Operate switch and hold.
  • Switch ignition ON.
  • Release switch after 5 seconds.
  • Repeat checking procedure to ensure no data remains in ECM fault memory.

Method 2

  • Ensure ignition switched OFF.
  • Disconnect ECM multi-plug or battery earth lead.

NOTE: ECM adaptive memory may be erased causing erratic running faults. Carry out road test to allow ECM to relearn basic values.
WARNING: Disconnecting the battery may erase memory from electronic units (e.g. radio, clock).


Audi  OBD 1 Trouble Codes

Flash type 4-digitFault locationProbable cause
0End of test sequence
1111Engine control module (ECM)ECM
1231Vehicle speed sensor (VSS)Wiring, speedometer, VSS
1232Idle speed control (ISC) actuatorWiring, multi-plug incorrectly wired, ISC actuator
2113
1
Crankshaft position (CKP) sensorInsecure rotor, wiring, CKP sensor
2121Closed throttle position (CTP) switchAccelerator cable adjustment, CTP switch adjustment, wiring, CTP switch
2212Throttle position (TP) sensorWiring, poor connection, TP sensor
2234Engine control module (ECM) – supply voltageBattery, wiring
2312Engine coolant temperature (ECT) sensorWiring, poor connection, ECT sensor
2322Intake air temperature (IAT) sensorWiring, IAT sensor
2341
2
Heated oxygen sensor (HO2S)
– lambda control
Heating inoperative, exhaust leak, misfire, fuel pressure/pump, EVAP canister purge valve
2342Heated oxygen sensor (HO2S)Wiring, HO2S, heating inoperative, fuel level low
2413
2
Mixture control (MC)Fuel level low, fuel pressure/pump, intake/exhaust leak, misfire, HO2S, EVAP canister purge valve, injector, excessive fuel in engine oil
4444No fault found
VAG type 5-digitFault locationProbable cause
0No fault found
281Vehicle speed sensor (VSS)Wiring, speedometer, VSS
282Idle speed control (ISC) actuatorWiring, multi-plug incorrectly wired, ISC actuator
00515
1
Crankshaft position (CKP) sensorInsecure rotor, wiring, CKP sensor
516Closed throttle position (CTP) switchAccelerator cable adjustment, CTP switch adjustment, wiring, CTP switch
518Throttle position (TP) sensorWiring, poor connection, TP sensor
522Engine coolant temperature (ECT) sensorWiring, poor connection, ECT sensor
523Intake air temperature (IAT) sensorWiring, IAT sensor
524Knock sensor (KS)Wiring, KS
525Heated oxygen sensor (HO2S)Wiring, HO2S, heating inoperative, fuel level low
532Engine control module (ECM) – supply voltageBattery, wiring
00537
2
Heated oxygen sensor (HO2S)
– lambda control
Heating inoperative, exhaust leak, misfire, fuel pressure/pump, EVAP canister purge valve
525Heated oxygen sensor (HO2S)Wiring, HO2S, heating inoperative, fuel level low
00561
2
Mixture control (MC)Fuel level low, fuel pressure/pump, intake/exhaust leak, misfire, HO2S, EVAP canister purge valve, injector, excessive fuel in engine oil
670Idle speed control (ISC) actuator position sensorWiring, throttle valve, ISC actuator position sensor
17978Engine control module (ECM) immobilizer activeIncorrect/damaged key, incorrectly coded, ECM/immobilizer replacement without coding, wiring, immobilizer defective
65535Engine control module (ECM)ECM

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