GM OBD/OBD2 Codes >> GM 92-95 C/K Pickup

GM

92-95 4.3, 5.0, 5.7, 7.4L VIN Z, H, K, N
Flash CodeFault LocationProbable Cause
12Start of diagnosisNo engine speed (RPM) signal received
13Oxygen sensor (O2S)/heated oxygen sensor (HO2S)Wiring open circuit, O2S/HO2S, ECM
14Engine coolant temperature (ECT) sensor – high temperature indicatedWiring short circuit to ground, ECT sensor, ECM
15Engine coolant temperature (ECT) sensor – low temperature indicatedWiring open circuit, ECT sensor, ECM
16 Vehicle speed sensor (VSS) buffer – signal lowWiring, VSS buffer, ECM
17 Camshaft 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 – low temperatureWiring open circuit, IAT sensor, ECM
24Vehicle speed sensor (VSS)Wiring open circuit/short circuit to ground, PROM, VSS, ECM
25Intake air temperature (IAT) sensor – high temperatureWiring short circuit to ground, IAT sensor, ECM
28               Transmission range (TR) switchWiring open circuit/short circuit to ground/short circuit to positive, TR switch, ECM
31 Engine speed control system – malfunctionWiring, throttle valve motor, throttle valve control module, ECM
32Exhaust gas recirculation (EGR) solenoidWiring open circuit/short circuit to ground, EGR valve, ECM
33Manifold absolute pressure (MAP) sensor – circuit malfunctionWiring open circuit/short circuit to positive, hose blocked/leaking, MAP sensor, ECM
34Manifold absolute pressure (MAP) sensor – circuit malfunctionWiring open circuit/short circuit to ground, MAP sensor, ECM
35 Idle air control (IAC) valveWiring, IAC valve, intake system leaking, fuel system, PCV valve, A/C system, mechanical fault, ECM
36Auxiliary idle air control valveWiring, idle air control valve, vacuum pipes, ECM
37Brake pedal position (BPP) switch for torque converter clutch (TCC)Wiring open circuit/short circuit to ground, incorrectly adjusted BPP switch, BPP switch, ECM
38Brake pedal position (BPP) switch/ torque converter clutch (TCC)Wiring open circuit/short circuit to ground, supply wire, BPP switch, TCC switch, ECM
39 Brake pedal position (BPP) switch – stuck OFFWiring, BPP switch, ECM
42Ignition control module (ICM) – electronic spark timing (EST)/ignition control (IC)/bypass circuit malfunctionWiring open circuit/short circuit to ground, ICM, ECM
43Knock sensor (KS)Wiring open circuit/short circuit to ground/short to positive, KS, PROM, ECM
44Oxygen sensor (O2S)/heated oxygen sensor (HO2S) – mixture leanWiring short circuit to ground, fuel pressure low, MAP sensor, misfire, fuel contamination, exhaust system leaking, O2S/HO2S, ECM
45Oxygen sensor (O2S)/heated oxygen sensor (HO2S) – mixture richFuel pressure high, injector(s) leaking, O2S contamination, EVAP canister purge valve, TP sensor, MAP sensor, EGR system, O2S/H2OS, ECM
46 Immobilizer system, code – malfunctionIncorrect key, ECM
51Engine control module (ECM) – PROMInsecure PROM, incorrect PROM, ECM
52  Engine control module (ECM) – malfunctionECM
52 (1994-1995) System Voltage – highAlternator, jump started
53 System Voltage – highAlternator
54Fuel pump circuit – voltage lowWiring open circuit/short circuit to ground, fuel pump relay, fuel pump, engine oil pressure warning lamp switch, ECM
55 Engine control module (ECM)Ground wiring open circuit, insecure PROM, ECM
58 Transmission fluid temperature (TFT) sensor – voltage lowWiring short circuit to ground, TFT sensor, ECM
59Transmission fluid temperature (TFT) sensor -voltage highWiring open circuit, TFT sensor, ECM
61 Oxygen sensor (O2S)O2S
62 Transmission gear switch signal circuitWiring open circuit/short circuit to ground, 2nd gear switch, 3rd gear switch, ECM
68 Torque converter clutch (TCC) – slippingWiring, TCC solenoid, transmission mechanical fault, ECM
69 Torque converter clutch (TCC) solenoid – stuck ONWiring open circuit/short circuit to ground, transmission internal wiring, TCC solenoid, transmission mechanical fault, ECM
70A/C refrigerant pressure sensor – voltage highWiring open circuit/short circuit to positive, A/C refrigerant pressure sensor, ECM
72Vehicle Speed Sensor (VSS)Wiring open circuit/short circuit to ground, VSS, ECM
73 Transmission fluid pressure (TFP) control solenoid – circuit malfunctionWiring, poor connection, TFP solenoid
74 Transmission input shaft speed sensor – circuit malfunctionWiring, input shaft speed sensor, ECM
75Exhaust gas recirculation (EGR) solenoid 1 – circuit malfunctionWiring, EGR valve, ECM
75 (1994-1995)System voltage, engine control module (ECM) – lowWiring, battery, alternator, ECM
76Exhaust gas recirculation (EGR) valve solenoid 2Wiring open circuit/short circuit to ground, supply wire, EGR valve, ECM
77Exhaust gas recirculation (EGR) valve solenoid 3Wiring open circuit/short circuit to ground, supply wire, EGR valve, ECM
79Transmission fluid temperature (TFT) – highTransmission mechanical fault, towing
80Torque converter clutch (TCC) – slippingWiring open circuit/short circuit to ground, supply wire, transmission internal wiring, TCC solenoid, transmission mechanical fault, ECM
81 Transmission shift solenoid (SS), 2nd-3rd – circuit malfunctionWiring, SS, ECM
82 (1994-1995) Transmission shift solenoid (SS), 1st-2nd – circuit malfunctionWiring, SS, ECM
83 Torque converter clutch (TCC) solenoid, pulse width modulated – circuit malfunctionWiring, TCC solenoid, ECUM
85 (1994-1995) Transmission input/output shaft speed, ratio variation – out of rangeWiring, input shaft speed sensor, output shaft speed sensor, mechanical fault
86 (1994-1995) Transmission input/output shaft speed, ratio variation – lower than expectedWiring, input shaft speed sensor, output shaft speed sensor, mechanical fault
87 (1994-1995) Transmission input/output shaft speed, ratio variation – out of rangeWiring, input shaft speed sensor, output shaft speed sensor, mechanical fault
90Torque converter clutch (TCC) – stuck ONWiring open circuit/short circuit to ground, transmission internal wiring, TCC solenoid, transmission mechanical fault, ECM
96Engine control module (ECM) – ignition supply voltage lowWiring open circuit, alternator, ECM
98Engine control module (ECM) – incorrectly codedECM incorrectly coded, ECM
99 Engine control module (ECM) – incorrectly codedECM incorrectly coded, ECM
 
Subscribe
Notify of
guest

This site uses Akismet to reduce spam. Learn how your comment data is processed.

9 Comments
most voted
newest oldest
Inline Feedbacks
View all comments
Travis
Travis
1 year ago

1993 Chevy blazer 1500 have fuel but no spark. Distributor cap and rotor replaced, plugs and wires, ignition coil and ignition cylinder all new within a year. And thoughts would be appreciated

Randy
Randy
11 months ago
Reply to  Travis

Travis,
I assumed you had a V8 in this truck. Should be the same for a V6.
Try this first.
Verify good power to the coil on the Pink wire while cranking.
Use a test light connected to the battery positive and touch the negative coil lead (White wire or Brown wire) when cranking the test light should blink. If it does, replace the coil.
If the test light does not blink while cranking, check the wire is good from the coil to the module. If it is, check ac voltage output from the pick-up coil to the module cranking with the pick-up coil disconnected from the back of the module. It should produce at least 0.7 volts ac. If less, replace the pick-up coil and if worn, the distributor shaft too.
If all this checks out, replace the ignition module.
Hope this helps.

Sean
Sean
1 year ago

Hey I don’t have a initial check code just flashes when checking

Jim
Jim
1 year ago

95 GMC 2500 diesel manual trans. check engine light comes on at 60 MPH. goes off if let up on throttle. comes back on soon. code is 78 not shown on code list. Previous code 72 speed sensor. Replaced sensor and no change. any suggestions/

Randy
Randy
1 year ago
Reply to  Jim

Jim,
That’s the code for the Wastegate solenoid fault. You can always try a wastegate solenoid to see but it would be best to diagnose the issue.
Also, there is a TSB for a revised flowchart to diagnose.
The TSB is #61-65-19A. Check it out and go thru the diagnosis.
If you still have issues please check with a tech that’s used to working on the older 6.5L engines in GM trucks.
Good luck with this issue Jim.

Randy
Randy
1 year ago
Reply to  Randy

BTW – the chart you referred to is for gas engines only. That’s why no code 78 in the chart.

Justin Fulton
Justin Fulton
3 years ago

I have a 1994 K1500 with 5.7 engine. When I check the codes I get a 67, 81, and 82. On the chart above there is no 67. I goes from 62 to 68,69, which are also for the “Wiring, TCC solenoid, transmission mechanical fault, ECM”. 81 and 82 is ” Wiring, SS, ECM”. On the previous chart on the other page it did show a 67 and said, “Wiring, SS, ECM”. I have had the ECM replaced in the last year, and the electronic ignition module replaced a couple of months ago. Right after that was changed the tach began erratically jumping about 4-500 RPMs. It doesn’t seem to me that that would be related to this. For some time now, the torque converter seems to unlock at around 40-45 RPMs, then not relock. Any suggestions how to proceed?

Nathaniel Olson
Nathaniel Olson
3 years ago

Hello. Does the engine overheat? This can be about 2 or 3 things. Is the engine misfiring? The strong gas smell can mean that the intake gaskets are leaking, or the fuel filter could need changed. Or an injector may be bad.The other thing it may be. The most likely thing, is a blown head gasket. Look for any misfiring code, if so, It’s pretty safe to say it has a blown head gasket.

fred schmidt
fred schmidt
3 years ago

engine dies when temp is at 210 and idles under 500 rpms, check engine light come on, does start up again and some white smoke from exhaust and strong gas smell. what could cause this?