GM OBD/OBD2 Codes >> G-Series – Jimmy – Sierra – Sonoma – Suburban – Yukon (1992 – 1995)

Model Year Engine identification System
G-Series 4.3/5.0/5.7/7.4L 1992-95 VIN  position 8 = H/K/N/Z GM
Jimmy 4.3L – without vehicle control module (VCM) 1992-95 VIN  position 8 = W/Z GM
Sierra C/K Pickup 4.3/5.0L 1992-95 VIN  position 8  = H/Z GM
Sierra C/K Pickup 5.7/7.4L 1992-95 VIN  position  8 = K/N GM
Sonoma 2.2/2.5/2.8L 1992-95 VIN  position 8 =  A/R/4 GM
Sonoma 4.3L – without vehicle control module (VCM) 1992-95 VIN  position  8 =  W/Z GM
Suburban 5.7/7.4L 1992-95 VIN  position  8  = K/N GM
Yukon  S.7L 1992-95 VIN  position 8 = K GM

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

  • Access data link connector (DLC).
  • Models with 12 pin data link connector (DLC).
o Jump data link connector (DLC) terminals A and B [1].  
  • Models with 16 pin data link connector (DLC).
o Jump data link connector (DLC) terminals 5 and 6 [2]
  • Switch ignition ON . 00 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:
o First group indicates the ‘tens’ of the trouble code [3] [A].
o Second group indicates the ‘units’ of the trouble code [3] [C].
o A short pause separates each group [3] [B].
o A long pause separates each trouble code [3] [D].
o For example: Trouble code 12 displayed [3] 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] or [2].

Erasing

NOTE: Disconnecting battery ground lead may cause driveability 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 rema in 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).

Trouble code  identification

Flash code Fault location Probable cause
12 Start of diagnosis No engine speed (RPM) signal received
13 Oxygen sensor (02S)/heated oxygen sensor(H02S) Wiring open circuit, 02S/H02S, ECM
14 Engine coolant temperature (ECT) sensorvoltage highllow Wiring, ECT sensor, ECM
15 Engine coolant temperature (ECT) sensor voltage high Wiring open circuit, ECT sensor, ECM
16 Vehicle speed sensor (VSS). -no signal Wiring, VSS, ECM
21 Throttle position (TP) sensor -voltage high/ low Wiring, TP sensor, ECM
22 Throttle position (TP) sensor -voltage low Wiring open circuit/short circuit to ground, TPsensor, ECM
23 Intake air temperature (IAT) sensor -voltage high Wiring, IAT sensor, ECM
24 Vehicle speed sensor (VSS) -no signal Wiring, VSS, ECM
25 Intake air temperature (IAT) sensor voltage low Wiring short circuit to ground, IAT sensor, ECM
26 Engine control module (ECM), quad driver/output driver -circuit malfunction Wiring, ECM controlled components, ECM D
27 Engine control module (ECM), quad driver! output driver -circuit malfunction Wiring, ECM controlled components, ECM D
28 Transmission gear pressure switch, signal -circuit malfunction Wiring open circuit/short circuit to ground, reverse/D1/D2/D3/D4 gear pressure switch(es), ECM
31 Throttle control system -malfunction Wiring, throttle control motor, throttle control module, ECM
32 Exhaust gas recirculation (EGR) solenoid Wiring, poor connections, EGR valve, ECM
33 Manifold absolute pressure (MAP) sensor voltage high Wiring, hose blockedlleaking, MAP sensor, ECM
34 Manifold absolute pressure (MAP) sensor voltage low Wiring open circuit/short circuit to ground, MAP sensor, ECM
35 Idle air control (lAC) valve Wiring, lAC valve, intake system leaking, fuel system, PCV valve, mechanical fault, ECM
36 Auxiliary idle air control valve Wiring, idle air control valve, vacuum pipes, ECM
37 Brake pedal position (BPP) switch for torque converter clutch (TCC) -stuck ON Wiring, BPP switch, ECM
38 [2] Brake pedal position (BPP) switch, torque converter clutch (TCC) -stuck OFF Wiring, BPP switch, ECM
38 [1] Knock sensor (KS) -circuit malfunction Wiring open circuit, KS, ECM
39 [1] Knock sensor (KS) -circuit malfunction Wiring short circuit, KS, ECM
39 [3] Brake pedal position (BPP) switch -stuck OFF Wiring, BPP switch, ECM
41 Crankshaft position (CKP) sensor, 1 X referencesignal -circuit malfunction Wiring, ICM, ECM
42 Ignition control , bypass/timing signal -circuit malfunction Wiring, poor connections, ICM, ECM
43 Knock sensor (KS)/knock control module circuit malfunction Wiring, KS, knock control module, ECM
44 Oxygen sensor (02S)/heated oxygen sensor (H02S) -mixture lean Wiring open circuit/short circuit to ground, injector(s) blocked, fuel contamination, fuel pressure low, exhaust system leaking, 025/H025, ECM
45 Oxygen sensor (02S)/heated oxygen sensor(H02S) -mixture rich Wiring open circuit, fuel pressure high, injector(s) leaking, 025/H025, EVAP purge valve, TP sensor,EGR system, ECM
51 Engine control module (ECM), PROM malfunction Poor connections, incorrect programming, ECM
52 [1] Engine control module (ECM) -malfunction ECM, poor connections
52 [2] System voltage high Alternator, jump started
53 System voltage high Alternator, jump started
54 Fuel pump circuit -voltage low Wiring open circuit/short circuit to ground, fuel pump relay, engine oil pressure warning lamp/fuel pump switch
55 Engine control module (ECM) -malfunction ECM
58 Transmission fluid temperature (TFT) sensorvoltage low Wiring short circuit to ground, TFT sensor, ECM
59 Transmission fluid temperature (TFT) sensor voltage high Wiring open circuit, TFT sensor, ECM
66 Transmission 3rd-2nd control solenoid -circuit malfunction Wiring, control solenoid, ECM
67 Torque converter clutch (TCC) solenoid -circuit malfunction Wiring, TCC solenoid, ECM
68 Torque converter clutch (TCC) -slipping Wiring, TCC solenoid, transmission mechanical fault, ECM
69 Torque converter clutch (TCC) solenoid -stuckON Wiring open circuit/short circuit to ground, transmission internal wiring, TCC solenoid, transmission mechanical fault, ECM
72 Vehicle speed sensor (VSS) -loss of signal Wiring, V55, ECM
73 Transmission fluid pressure (TFP) control solenoid -circuit malfunction Wiring, poor connection, TFP solenoid
74 Transmission input shaft speed sensor circuit malfunction Wiring, input shaft speed sensor, ECM
75 System voltage low, engine control module (ECM) Wiring, battery, alternator, ECM
79 Transmission fluid temperature (TFT) high Transmission mechanical fault, towing weight limit exceeded
81 Transmission shift solenoid (SS), 2nd-3rd circuit malfunction Wiring, 55, ECM
82 Transmission shift solenoid (88), 1st-2nd circuit malfunction Wiring, 55, ECM
83 Torque converter clutch (TCC) solenoid, pulse width modulated -circuit malfunction Wiring, TCC solenoid, ECM
85 Transmission input/output shaft speed, ratio variation -out of range Wiring, input shaft speed sensor, output shaft speed sensor, mechanical fault
86 Transmission input/output shaft speed, ratio variation -lower than expected Wiring, input shaft speed sensor, output shaft speed sensor, mechanical fault
87 Transmission input/output shaft speed, ratio variation -higher than expected Wiring, input shaft speed sensor, output shaft speed sensor, mechanical fault
  Use of the vehicle wiring diagram is recommended to confirm which components are fitted.
o A/C compressor clutch relay
o A/C condenser blower motor relay
o Engine coolant blower motor relay
o Engine coolant ‘hot’ warning lamp
o Evaporative emission (EVAP) canister purge valve
o Exhaust gas recirculation (EGR) solenoid
o Malfunction indicator lamp (MIL)
o Torque converter clutch (TCC) solenoid
o Transmission shift solenoids (S8)
o Transmission shift warning lamp (MT)