Pontiac OBD/OBD2 Codes >> Firebird 3.4L – Grand AM 3.1L – Grand Prix 3.1L (1993 – 1995)

ModelYearEngine identificationSystem
Firebird 3.4L1993-95VIN  position 8 = SGM
Grand AM  3.1 L1994-95VIN  position 8 = MGM
Grand Prix 3.1 L1994-95VIN  position 8 = T/MGM

General information

  • Malfunction indicator lamp (MIL) will illuminate if certain faults are recorded.
  • ECM operates in backup mode if sensors fail, to enable vehicle to be driven to repair shop.
  • Trouble codes can be displayed by the MIL or by using a Scan Tool connected to the data link connector (DLC).

Accessing

Models with data link connector (OLe) terminal B connected

  • Access data link connector (DLC).
  • Jump data link connector (DLC) terminals A and B [1].
  • Switch ignition ON. Do NOT start engine.
  • Count MIL flashes. Note trouble codes. Compare with trouble code table.
  • Firstly trouble code 12 will be displayed 3 times.
  • Trouble codes consist of 2 groups, displayed as follows:
  • First group indicates the ‘tens’ of the trouble code [2] [A].
  • Second group indicates the ‘units’ of the trouble code [2] [C].
  • A short pause separates each group [2] [B].
  • A long pause separates each trouble code [2] [D).
  • For example: Trouble code 12 displayed fl. Start of diagnosis.
  • Each additional trouble code will now be displayed 3 times, in ascending order.
NOTE: If no additional trouble codes are stored, code 12 will continue to be displayed.
  • Trouble codes can also be displayed by using a Scan Tool connected to the data link connector (DLC) 1

Models without data link connector (DLC) terminal 8 connected

• Trouble codes can only be displayed by using a Scan Tool connected to the data link connector (DLC) 1.

Erasing

NOTE: Disconnecting battery ground lead may cause driveabi/ity problems until the engine management system relearns basic values.
  • Ensure ignition switched OFF.
  • Disconnect battery ground cable for 30 seconds.
  • Reconnect battery ground cable .
  • Repeat checking procedure to ensure no trouble codes remain in ECM fault memory.
NOTE: Disconnecting battery ground lead may also erase memory from electronic units, such as radio.
• Trouble codes can also be erased by using a Scan Tool connected to the data link connector (DLC) 1.

Trouble code  identification

Flash codeFault locationProbable cause
12Start of diagnosisNo engine speed (RPM) signal received
13 DHeated oxygen sensor (H02S)Wiring open circuit, H02S, ECM
13 f)Oxygen sensor (028), bank 2Wiring open circuit, 02S, ECM
14Engine coolant temperature (ECT) sensor voltagelowWiring short circuit to ground, ECT sensor, ECM
15Engine coolant temperature (ECT) sensor voltagehighWiring open circuit, ECT sensor, ECM
16System voltage lowWiring, alternator
17Camshaft position (CMP) sensor -circuit malfunctionWiring, CMP sensor, mechanical fault, ECM
21Throttle position (TP) sensor -voltage highWiring open circuit/short circuit to positive, TP sensor, ECM
22Throttle position (TP) sensor -voltage lowWiring open circuit/short circuit to ground, TP sensor,ECM
23Intake air temperature (IAT) sensor -voltage highWiring open circuit, IAT sensor, ECM
24Vehicle speed sensor (VSS) -no signalWiring, VSS, ECM
25Intake air temperature (IAT) sensor -voltage lowWiring short circuit to ground, IAT sensor, ECM
28Transmission range (TR) switch -malfunctionWiring, TR switch, ECM
33Manifold absolute pressure (MAP) sensor voltage highWiring short circuit to positive, hose blockedl leaking, MAP sensor, ECM
34Manifold absolute pressure (MAP) sensor voltagelowWiring open circuit/short circuit to ground, MAP sensor, ECM
35Idle air control (lAC) valveWiring open circuit/short circuit to groundl short circuit to positive, lAC valve, intake system leaking,fuel system, PCV valve, AlC system, mechanical fault, ECM
36Crankshaft position (CKP) sensor, at crankshaft pulley -24X signal circuit malfunctionWiring, CKP sensor, ECM
37Brake pedal position (BPP) switch for torque converter clutch (TCC)Wiring, incorrectly adjusted, BPP switch, ECM
39Clutch pedal position (CPP) switchWiring, incorrectly adjusted, CPP switch, ECM
41Ignition control. timing signal -circuit malfunctionWiring, poor connections, ICM, ECM
42Ignition control. bypass signal -circuit malfunctionWiring, poor connections, ICM, ECM
43Knock sensor (KS) -circuit malfunctionWiring, K5, ECM
44 1Heated oxygen sensor (H028) mixture leanWiring open circuit/short circuit to ground, injector(s)blocked, fuel contamination, fuel pressure low,exhaust system leaking, H025, ECM
44 2Oxygen sensor (028). bank 2 -mixture leanWiring open circuit/short circuit to ground, injector(s) blocked, fuel contamination, fuel pressure low,exhaust system leaking, 025, ECM
45 1Heated oxygen sensor (H02S) -mixture richWiring open circuit, fuel pressure high, injector(s) leaking, H025, EVAP purge valve, throttle position (TP) sensor, EGR system, ECM
45 2Oxygen sensor (028). bank 2 -mixture richWiring open circuit, fuel pressure high, injector(s) leaking, 025, EVAP purge valve, throttle position (TP) sensor, EGR system, ECM
46Immobilizer system. code -malfunctionIncorrect key, immobilizer control module, ECM
51Engine control module (ECM). PROM malfunctionPoor connections, incorrect programming, ECM
53System voltage highAlternator
54Fuel pump circuit -voltage lowWiring open circuit/short circuit to ground, fuel pump relay, engine oil pressure warning lamp/ fuel pump switch
58Transmission fluid temperature (TFT) sensorvoltage lowWiring short circuit to ground, TFT sensor, ECM
59Transmission fluid temperature (TFT) sensorvoltage highWiring open circuit, TFT sensor, ECM
61AlC system -performanceRefrigerant low, wiring, AlC refrigerant pressure sensor, AlC evaporator temperature sensor, ECM
63Oxygen sensor (028). bank 1Wiring open circuit, 025, ECM
64Oxygen sensor (028). bank 1 -mixture leanWiring open circuit/short circuit to ground, injector(s) blocked, fuel contamination, fuel pressure low,exhaust system leaking, 025, ECM
65Oxygen sensor (02S). bank 1 -mixture richWiring open circuit, fuel pressure high, injector(s) leaking, 025, EVAP purge valve, throttle position (TP) sensor, EGR system, ECM
66AlC refrigerant pressure sensor -voltage lowWiring open circuit/short circuit to ground, AlC refrigerant pressure sensor, ECM
67AlC refrigerant pressure sensor -circuit malfunctionWiring open circuit, AlC refrigerant pressure sensor,ECM
68AlC compressor clutch relay -circuit malfunctionWiring short circuit, AlC compressor clutch relay, ECM
69AlC compressor clutch relay -circuit malfunctionWiring open circuit, AlC compressor clutch relay, ECM
70AlC refrigerant pressure sensor -voltage highWiring open circuit/short circuit to positive, AlCrefrigerant pressure sensor, ECM
71AlC evaporator temperature sensor -voltage highWiring, poor connections, AlC evaporator temperaturesensor
72Vehicle speed sensor (VSS) -circuit malfunctionWiring, VSS, ECM
73AlC evaporator temperature sensor -voltage lowWiring, poor connections, AlC evaporator temperature sensor
75Exhaust gas recirculation (EGR) solenoid 1 circuit malfunctionWiring, EGR valve, ECM
76Exhaust gas recirculation (EGR) solenoid 2 circuit malfunctionWiring, EGR valve, ECM
77Exhaust gas recirculation (EGR) solenoid 3 circuit malfunctionWiring, EGR valve, ECM
79Transmission fluid temperature (TFT) highTransmission mechanical fault, towing weight limitexceeded
80Torque converter clutch (TCC) -slippingWiring, TCC solenoid, transmission mechanical fault,ECM
81Brake pedal position (BPP) switch, torque converter clutch (TCC) -circuit malfunctionWiring, BPP switch, ECM
82Crankshaft position (CKP) sensor, in cylinder block-3X signal circuit malfunctionWiring open circuit/short circuit to ground, CKP sensor, ICM
85Engine control module (ECM), PROM malfunctionPoor connections, incorrect programming, ECM
86Engine control module (ECM) -analogue/digital converterAlC refrigerant pressure sensor/knock sensor(KS)/engine coolant temperature (ECT) sensor/ fuel pump monitor circuit short circuit to battery voltage
87Engine control module (ECM), EEPROM malfunctionPoor connections, incorrect programming, ECM
90Torque converter clutch (TCC) -stuck ONWiring open circuit/short circuit to ground, transmission internal wiring, TCC solenoid, transmission mechanical fault, ECM
93Transmission fluid pressure (TFP) control solenoid -circuit malfunctionWiring, poor connection, TFP solenoid
96Engine control module (ECM) -ignition supply voltage lowWiring open circuit, alternator, ECM
98Engine control module (ECM) -incorrectly codedECM incorrectly coded, ECM
99Engine control module (ECM) -incorrectly codedECM incorrectly coded, ECM