1985 to 1991

Code #12: Normal No Codes.
Code #13: Open Oxygen Sensor Circuit.
Code #14: Coolant Sensor Circuit Low.
Code #15: Coolant Sensor Circuit High.
Code #21: Throttle Position Sensor High.
Code #22: Throttle Position Sensor Low.
Code #23: Manifold Air Temperature Circuit High.
Code #24: Vehicle Speed Sensor.
Code #25: Manifold Air Temperature Circuit Low.
Code #32: EGR System Failure.
Code #33: Mass Air Flow Sensor High.
Code #34: Mass Air Flow Sensor Low.
Code #36: Mas Air Flow Sensor Burn-Off Function Fault.
Code #41: Cylinder Select Error.
Code #42: Electronic Spark Timing.
Code #43: Electronic Spark Control.
Code #44: Lean Exhaust indication.
Code #45: Rich Exhaust Indication.
Code #46: Vehicle Anti Theft Fault.
Code #51: Faulty Mem-Cal.
Code #52: Fuel Calpak Missing.
Code #52(1990-91 Corvette Only): Engine Oil Temperature Sensor Low.
Code #53: System Over Voltage.
Code #54: Fuel Pump Circuit Low Voltage.
Code #55: Defective ECM.
Code #62: Engine Oil Temperature Sensor Circuit High.

ECM CODES 1992 TO 1993:

Code #12: Normal No Codes.
Code #13: Left Oxygen Sensor Circuit.
Code #14: Coolant Temperature Sensor Circuit High.
Code #15: Coolant Temperature Sensor Circuit Low.
Code #16: Opti-Spark Ignition Timing System.( Low Pulse)
Code #21: Throttle Position Sensor Circuit High.
Code #22: Throttle Position Sensor Circuit Low.
Code #23: Intake Air Temperature Sensor Circuit Low.
Code #24: Vehicle Speed Sensor Circuit.
Code #25: Intake Temperature Sensor Circuit High.
Code #26: Quad-Driver Module #1 Circuit.
Code #27: Quad-Driver Module #2 Circuit.
Code #28: Quad-Driver Module #3 Circuit.
Code #32: Exhaust Gas Recirclation Circuit.
Code #33: Manifold Absolute Pressure Sensor Circuit Low.
Code #34: Manifold Absolute Pressure Sensor Circuit High.
Code #36: Opti-Spark Ignition Timing System. (High Resolution Pulse.)
Code #41: Electronic Spark Timing Circuit Open.
Code #42: Electronic Spark Timing Circuit Grounded.
Code# 43: Electronic Spark Control Circuit.
Code #44: Left Oxygen Sensor Circuit Lean.
Code #45: Left Oxygen Sensor Circuit Rich.
Code #51: Mem-Cal Error.
Code #52: Engine Oil Temperature Sensor Circuit Low.
Code #53: System Voltage.
Code #55: Fuel Lean Monitor.
Code #56: Vacuum Sensor Circuit.
Code #61: Secondary Port Throttle Valve System.
Code #62: Engine Oil Temperature Sensor Circuit High.
Code #63: Right Oxygen Sensor Circuit Open.
Code #64: Right Oxygen Sensor Circuit Lean.
Code #65: Right Oxygen Sensor Circuit Rich.
Code #66: A/C Pressure Sensor Circuit Open.
Code #67: A/C Pressure Sensor Circuit. (Sensor or A/C Clutch Circuit Problem)
Code #68: A/C Relay Circuit Shorted.
Code #69: A/C Clutch Circuit.
Code #72: Gear Selector Switch Circuit.

More
CODES 1994 TO 1996:

DTC #11: Malfunction Indicator Lamp Circuit.
DTC #13: Bank #1 Heated Oxygen Sensor #1 Circuit:
DTC #14: Engine Coolant Temperature Sensor Circuit Voltage Low.
DTC #15: Engine Coolant Temperature Sensor Circuit Voltage High.
DTC #16: Distributor Ignition System Low Pulse.
DTC #18: Injector Circuit.
DTC #21: Throttle Position Sensor Circuit Voltage High.
DTC #22: Throttle Position Sensor Circuit Voltage Low.
DTC #23: Intake Temperature Sensor Circuit Voltage High.
DTC #24: Vehicle Speed Sensor Circuit.
DTC #25: Intake Air Temperature Sensor Circuit Voltage Low.
DTC #26: Evaporative Emission Canister Purge Solenoid Valve Circuit.
DTC #27: EGR Vacuum Control Signal Solenoid Valve Circuit.
DTC #28: Transmission Range Pressure Switch Assembly Fault.
DTC #29: Secondary Air Injection Pump Circuit.
DTC #32: Exhaust Gas Recalculation.
DTC #33: Manifold Absolute Pressure Sensor Circuit High.
DTC #34: Manifold Absolute Pressure Sensor Circuit Low.
DTC #36: Distributor Ignition System High Pulse.
DTC #37: Brake Switch Stuck On.
DTC #38: Brake Switch Stuck Off.
DTC #41: Ignition Control Circuit Open.
DTC #42: Ignition Control Circuit Shorted.
DTC #43: Knock Sensor Circuit.
DTC #44: Bank 1 LF Heated Oxygen Sensor #1 Circuit Lean.
DTC #45: Bank 1 LF Heated Oxygen Sensor #1 Circuit Rich.
DTC #47: Knock Sensor Circuit Or Module Missing.
DTC #48: Mass Air Flow Sensor Circuit.
DTC #50: System Voltage Low.
DTC #51: EEPROM Programming Error.
DTC #52: Engine Oil Temperature Sensor Circuit Voltage Low.
DTC #53: System Voltage Low.
DTC #55: Fuel Lean Monitor.
DTC #58: Transmission Fluid Temperature Sensor Circuit Low.
DTC #59: Transmission Fluid Temperature Sensor Circuit High.
DTC #62: Engine Oil Temperature Sensor Circuit Voltage Low.
DTC #63: Bank 2 RF Heated Oxygen Sensor #1 Circuit Open.
DTC #64: Bank 2 RF Heated Oxygen Sensor #1 Circuit Lean.
DTC #65: Bank 2 RF Heated Oxygen Sensor #1 Circuit Rich.
DTC #66: A/C Refrigerant Pressure Sensor Circuit Open.
DTC #67: A/C Pressure Sensor Circuit Sensor or A/C Clutch.
DTC #68: A/C Relay Circuit.
DTC #69: A /C Clutch Circuit.
DTC #70: A/C Clutch Relay Driver Circuit.
DTC #72: Vehicle Speed Sensor Loss.
DTC #73: Pressure Control Solenoid Circuit Current Error.
DTC #74: Traction Control System Circuit Low.
DTC #75: Transmission System Voltage Low
DTC #77: Primary Cooling Fan Relay Control Circuit.
DTC #78: Secondary Cooling Fan Relay Control Circuit.
DTC #79: Transmission Fluid Overtemp.
DTC #80: Transmission Component Slipping.
DTC #81: Transmission 2-3 Shift Solenoid Circuit.
DTC #82: Transmission 1-2 Shift Solenoid Circuit.
DTC #83: Torque Converter Solenoid Voltage High.
DTC #84: 3-2 Control Solenoid Circuit.(Auto Only).
DTC #84: 2nd And 3rd Gear Blockout Relay Control Circuit.
DTC #85: Transmission TCC Stock On.
DTC #90: Transmission TCC Solenoid Circuit.
DTC #91: One To Four Upshift Lamp(Manual Only).
DTC #97: VSS Output Circuit.
DTC #98: Tachometer Output Signal Voltage Wrong.

**************************************** ****************
1996
Engine DTC's

DTC P0100 MAF Sensor Circuit Insufficient Activity
DTC P0101 Mass Air Flow (MAF) Sensor Performance
DTC P0102 Mass Air Flow (MAF) Sensor Circuit Low Frequency
DTC P0103 Mass Air Flow (MAF) Sensor Circuit High Frequency
DTC P0106 Manifold Absolute Pressure (MAP) System Performance
DTC P0107 Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage
DTC P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage
DTC P0112 Intake Air Temperature (IAT) Sensor Circuit Low Voltage
DTC P0113 Intake Air Temperature (IAT) Sensor Circuit High Voltage
DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage
DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage
DTC P0121 TP Sensor Circuit Insufficient Activity
DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage
DTC P0123 Throttle Position (TP) Sensor Circuit High Voltage
DTC P0125 Engine Coolant Temperature (ECT) Insufficient for Closed Loop Fuel Control
DTC P0131 HO2S Circuit Low Voltage Bank 1 Sensor 1
DTC P0132 HO2S Circuit High Voltage Bank 1 Sensor 1
DTC P0133 HO2S Slow Response Bank 1 Sensor 1
DTC P0134 HO2S Circuit Insufficient Activity Bank 1 Sensor 1
DTC P0135 HO2S Heater Performance Bank 1 Sensor 1
DTC P0137 HO2S Circuit Low Voltage Bank 1 Sensor 2
DTC P0138 HO2S Circuit High Voltage Bank 1 Sensor 2
DTC P0140 HO2S Circuit Insufficient Activity Bank 1 Sensor 2
DTC P0141 HO2S Heater Performance Bank 1 Sensor 2
DTC P0151 HO2S Circuit Low Voltage Bank 2 Sensor 1
DTC P0152 HO2S Circuit High Voltage Bank 2 Sensor 1
DTC P0153 HO2S Slow Response Bank 2 Sensor 1
DTC P0154 HO2S Circuit Insufficient Activity Bank 2 Sensor 1
DTC P0155 HO2S Heater Performance Bank 2 Sensor 1
DTC P0157 HO2S Circuit Low Voltage Bank 2 Sensor 2
DTC P0158 HO2S Circuit High Voltage Bank 2 Sensor 2
DTC P0160 HO2S Circuit Insufficient Activity Bank 2 Sensor 2
DTC P0161 HO2S Heater Performance Bank 2 Sensor 2
DTC P0171 Fuel Trim System Lean Bank 1
DTC P0172 Fuel Trim System Rich Bank 1
DTC P0174 Fuel Trim System Lean Bank 2
DTC P0175 Fuel Trim System Rich Bank 2
DTC P0200 Injector Control Circuit
DTC P0300 Engine Misfire Detected
DTC P0323 DI Low/High Resolution Circuit Intermittent
DTC P0325 Knock Sensor Module Performance
DTC P0327 Knock Sensor (KS) Circuit Bank 1
DTC P0332 Knock Sensor (KS) Circuit Bank 2
DTC P0335 Crankshaft Position (CKP) Sensor Circuit
DTC P0336 Crankshaft Position (CKP) Sensor Performance
DTC P0372 DI High Resolution Circuit
DTC P0400 Exhaust Gas Recirculation (EGR) System Performance
DTC P0403 Exhaust Gas Recirculation (EGR) Solenoid Control Circuit
DTC P0410 Secondary Air Injection (AIR) System
DTC P0412 Secondary Air Injection (AIR) Relay Control Circuit
DTC P0420 Catalyst System Low Efficiency Bank 1
DTC P0430 Catalyst System Low Efficiency Bank 2
DTC P0441 Evaporative Emission (EVAP) System No Flow During Purge
DTC P0443 Evaporative Emission (EVAP) Purge Solenoid Control Circuit
DTC P0500 Vehicle Speed Sensor (VSS) Circuit
DTC P0506 Idle Speed Low
DTC P0507 Idle Speed High
DTC P0530 Air Conditioning (A/C) Refrigerant Pressure Sensor Circuit
DTC P0531 Air Conditioning (A/C) Refrigerant Pressure Sensor Performance
DTC P0562 System Voltage Low
DTC P0563 System Voltage High
DTC P0601 Control Module Read Only Memory (ROM)
DTC P0602 Control Module Not Programmed
DTC P1107 Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent Low Voltage
DTC P1111 Intake Air Temperature (IAT) Sensor Circuit Intermittent High Voltage
DTC P1112 Intake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage
DTC P1114 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage
DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage
DTC P1121 Throttle Position (TP) Sensor Circuit Intermittent High Voltage
DTC P1122 Throttle Position (TP) Sensor Circuit Intermittent Low Voltage
DTC P1133 HO2S Insufficient Switching Bank 1 Sensor 1
DTC P1134 HO2S Transition Time Ratio Bank 1 Sensor 1
DTC P1153 HO2S Insufficient Switching Bank 2 Sensor 1
DTC P1154 HO2S Transition Time Ratio Bank 2 Sensor 1
DTC P1171 Fuel System Lean During Acceleration
DTC P1187 EOT Sensor Circuit Low Voltage
DTC P1188 EOT Sensor Circuit High Voltage
DTC P1222 Injector Control Circuit Intermittent
DTC P1351 Ignition Coil Control Circuit High Voltage
DTC P1361 Ignition Coil Control Circuit Low Voltage
DTC P1371 DI Low Resolution Circuit
DTC P1380 Misfire Detected - Rough Road Data Not Available
DTC P1381 Misfire Detected - No Communication with Brake Control Module
DTC P1415 Secondary Air Injection (AIR) System Bank 1
DTC P1416 Secondary Air Injection (AIR) System Bank 2
DTC P1441 Evaporative Emission (EVAP) System Flow During Non-Purge
DTC P1508 Idle Speed Low - Idle Air Control (IAC) System Not Responding
DTC P1509 Idle Speed High - Idle Air Control (IAC) System Not Responding
DTC P1539 Air Conditioning (A/C) Clutch Feedback Circuit High Voltage
DTC P1545 Air Conditioning (A/C) Clutch Relay Control Circuit
DTC P1546 Air Conditioning (A/C) Clutch Feedback Circuit Low Voltage
DTC P1572 ASR/TCS Active CKT Low Voltage Too Long
DTC P1641 Cooling Fan Relay 1 Control Circuit
DTC P1642 Cooling Fan Relay 2 and 3 Control Circuit
DTC P1643 Engine Speed Output Circuit
DTC P1652 Vehicle Speed Output Circuit
DTC P1657 Skip Shift Solenoid Control Circuit
DTC P1661 Malfunction Indicator Lamp (MIL) Control Circuit
DTC P1664 Skip Shift Lamp Control Circuit

Transmission DTC's

DTC P0502 Vehicle Speed Sensor (VSS) Circuit Low Input
DTC P0560 System Voltage
DTC P0712 Transmission Fluid Temperature (TFT) Sensor Circuit Low Input
DTC P0713 Transmission Fluid Temperature (TFT) Sensor Circuit High Input
DTC P0719 Brake Switch Circuit Low Input
DTC P0724 Brake Switch Circuit High Input
DTC P0742 TCC System Stuck On
DTC P0748 Pressure Control Solenoid Circuit Electrical
DTC P0751 1-2 Shift Solenoid Valve Performance
DTC P0753 1-2 Shift Solenoid Circuit Electrical
DTC P0756 2-3 (B) Shift Solenoid Performance
DTC P0758 2-3 (B) Shift Solenoid Electrical
DTC P1572 TCS Active Circuit Low Voltage Too Long
DTC P1810 TFP Valve Position Switch Circuit
DTC P1812 Transmission Fluid Overtemperature
DTC P1860 TCC PWM Solenoid Circuit Electrical
DTC P1864 TCC Solenoid Electrical
DTC P1870 Transmission Component Slipping
DTC P1886 3-2 SS Valve Assembly

Thanks, helpful -- any tuners you'd recommend?

Paper clip from pin 12 to ground (4 or 5 are both ground)

On a 94-96 you can check the codes with a paper clip as follows:

You short pin "12" to pin "4" and turn the ignition switch to "On" without starting the engine.

The speedometer will display any codes using the same protocol as the 1990-1993 model but there are some changes in the designation for the modules plus additional modules are added:

Module "1" is still the CCM module.

Module "4" is now called the PCM module (Powertrain Control Module) because automatic transmission computer control was added to Engine Control Module in 1994.

Module 7 (on the 1996 model only) is the RTD module. (This is the Real Time Dampening module which replaced the Selective Ride Control module in 1996).

Module 9 is the ABS/ASR module number from 1994 through 1996.
Finally, Module "A", the DERM (Dynamic Energy Control Module --- (the air bag control module) will be requested to show any codes.

Just like the 1990-1993 display, you read the codes on the speedometer (big) and read the module number on the trip odometer (small).

A series of dashed lines for instance “ - - -“ indicates no more stored codes for that module.

A code showing as “C12” for the CCM module (module #1) means no codes are stored. So C12 is a good thing to see.

Again, you can cause the codes to repeat by turning the ignition off for five seconds and then back on.

Turn the ignition off and remove the short to restore normal operation.

To clear the codes,

1. With ignition "off" ground terminal #12 of the DLC (use bent paper clip to connect pin 4 to pin 12)

2. Turn ignition "on".

3. Press trip/odo button on the DIC until 1.7 appears in the trip
monitor area of the instrument cluster.

4. Press eng/met button on the DIC & hold until "---" appears in the
speedometer area of the cluster, this will clear CCM DTC'S.


To clear PCM/ECM codes do the following:


1. Press the trip reset button on the DIC until the desired system is displayed. In this case it will be 4.0.

2. Press trip/odo button on the DIC until the desired diagnostic mode(4.7) is displayed on the trip monitor area of the cluster.

3. Press & hold the eng/met button on the DIC until "---" is
displayed in the speedometer area of the cluster, this will clear PCM codes.


To clear ABS/ASR codes do the following:

Same as above but you’re looking for “9.7” on the trip odo

And here are the codes

1994-1995: Diagnostic Trouble Codes
DTC #11: Malfunction Indicator Lamp Circuit.
DTC #13: Bank #1 Heated Oxygen Sensor #1 Circuit:
DTC #14: Engine Coolant Temperature Sensor Circuit Voltage Low.
DTC #15: Engine Coolant Temperature Sensor Circuit Voltage High.
DTC #16: Distributor Ignition System Low Pulse.
DTC #18: Injector Circuit.
DTC #21: Throttle Position Sensor Circuit Voltage High.
DTC #22: Throttle Position Sensor Circuit Voltage Low.
DTC #23: Intake Temperature Sensor Circuit Voltage High.
DTC #24: Vehicle Speed Sensor Circuit.
DTC #25: Intake Air Temperature Sensor Circuit Voltage Low.
DTC #26: Evaporative Emission Canister Purge Solenoid Valve Circuit.
DTC #27: EGR Vacuum Control Signal Solenoid Valve Circuit.
DTC #28: Transmission Range Pressure Switch Assembly Fault.
DTC #29: Secondary Air Injection Pump Circuit.
DTC #32: Exhaust Gas Recalculation.
DTC #33: Manifold Absolute Pressure Sensor Circuit High.
DTC #34: Manifold Absolute Pressure Sensor Circuit Low.
DTC #36: Distributor Ignition System High Pulse.
DTC #37: Brake Switch Stuck On.
DTC #38: Brake Switch Stuck Off.
DTC #41: Ignition Control Circuit Open.
DTC #42: Ignition Control Circuit Shorted.
DTC #43: Knock Sensor Circuit.
DTC #44: Bank 1 LF Heated Oxygen Sensor #1 Circuit Lean.
DTC #45: Bank 1 LF Heated Oxygen Sensor #1 Circuit Rich.
DTC #47: Knock Sensor Circuit Or Module Missing.
DTC #48: Mass Air Flow Sensor Circuit.
DTC #50: System Voltage Low.
DTC #51: EPROM Programming Error.
DTC #52: Engine Oil Temperature Sensor Circuit Voltage Low.
DTC #53: System Voltage Low.
DTC #55: Fuel Lean Monitor.
DTC #58: Transmission Fluid Temperature Sensor Circuit Low.
DTC #59: Transmission Fluid Temperature Sensor Circuit High.
DTC #62: Engine Oil Temperature Sensor Circuit Voltage Low.
DTC #63: Bank 2 RF Heated Oxygen Sensor #1 Circuit Open.
DTC #64: Bank 2 RF Heated Oxygen Sensor #1 Circuit Lean.
DTC #65: Bank 2 RF Heated Oxygen Sensor #1 Circuit Rich.
DTC #66: A/C Refrigerant Pressure Sensor Circuit Open.
DTC #67: A/C Pressure Sensor Circuit Sensor or A/C Clutch.
DTC #68: A/C Relay Circuit.
DTC #69: A /C Clutch Circuit.
DTC #70: A/C Clutch Relay Driver Circuit.
DTC #72: Vehicle Speed Sensor Loss.
DTC #73: Pressure Control Solenoid Circuit Current Error.
DTC #74: Traction Control System Circuit Low.
DTC #75: Transmission System Voltage Low
DTC #77: Primary Cooling Fan Relay Control Circuit.
DTC #78: Secondary Cooling Fan Relay Control Circuit.
DTC #79: Transmission Fluid Overtemp.
DTC #80: Transmission Component Slipping.
DTC #81: Transmission 2-3 Shift Solenoid Circuit.
DTC #82: Transmission 1-2 Shift Solenoid Circuit.
DTC #83: Torque Converter Solenoid Voltage High.
DTC #84: 3-2 Control Solenoid Circuit.(Auto Only).
DTC #84: 2nd And 3rd Gear Blockout Relay Control Circuit.
DTC #85: Transmission TCC Stock On.
DTC #90: Transmission TCC Solenoid Circuit.
DTC #91: One To Four Upshift Lamp(Manual Only).
DTC #97: VSS Output Circuit.
DTC #98: Tachometer Output Signal Voltage Wrong.

To run a diagnostic on the PKE system, connect pins 4 and 8 on the ALDL (see pic below to see pin label order)


And the PKE diagnostic system works as follows:
With pins 4 and 8 connected, the PKE light in the Driver Info Centre will flash the codes.

Here is the list of DTCs and what they mean:

DTC #12: Receiver Memory Bad
DTC #13: Transmitter Not in Range
DTC #14: Non-Valid Transmitter Received
DTC #15: Valid Transmitter Received
DTC #16: Passenger Door Button Depressed
DTC #17: Hatch Button Depressed

i have a 92 vett it doesn't run right ,
idle bad shaking like miss fire no power at all
got the code pin 5 and 6
12 12 12 28 28 28 12 12 12
and when I go to pin 6 and 7
1. C12
4. H32
7. Err
9. Err
Can you show me where to check
i am glad it said C 12 ...
Thanks :happy0045:

whats a good way to check codes on a 85 vette?

whats a good way to check codes on a 85 vette?

To see which trouble code or codes are being set in your ECM is to jumper the A and B pins of the 12 pin ALDL OBD1 connector with a paper clip. While the car is off, sitting still, turn the ignition key forward while this jumper is in place. Do not start the car. The Service Engine Soon ( SES ) light will flash in a repeating sequence, telling which trouble codes have been set in the ECM.

To see which trouble code or codes are being set in your ECM is to jumper the A and B pins of the 12 pin ALDL OBD1 connector with a paper clip. While the car is off, sitting still, turn the ignition key forward while this jumper is in place. Do not start the car. The Service Engine Soon ( SES ) light will flash in a repeating sequence, telling which trouble codes have been set in the ECM.

Thanks for the simple explanation :iagree:...it was concise and easy to understand. That and the codes in prior post make a good thing to have in the shop manual for easy reference. :toocrazy:

92 / 93 info can be found here (http://www.corvettepics.net/misc/ccm-codepull.pdf)

Thanks to C4Guru AKA Andy.