1991 l98/auto 'SYS" question
Cruising
Joined: Sep 2006
Posts: 14
Likes: 0
From: Clovis, California
Take a look at this link ... and see if you can get the codes ...
http://www.c4guru.com/articles/CCMCodePull.pdf
http://www.c4guru.com/articles/CCMCodePull.pdf
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
The link above is for the 92-93 vettes.
Ground terminal A and B of the ALDL connector. Turn the key on.
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.
Ground terminal A and B of the ALDL connector. Turn the key on.
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.
Cruising
Joined: Sep 2006
Posts: 14
Likes: 0
From: Clovis, California
Sorry ... posted the ECM / CCM link too quickly (been working with an ECM / CCM issue for the last couple of weeks now and posted the wrong link) 
RRT Vette gave you the correct codes ...
Good luck ...
RRT Vette gave you the correct codes ...
Good luck ...
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
I have a 91.
Use a paper clip to connect A & B together.
IIRC it doesn't work if you ground A & B. It may but the procedure calls for A & B to be jumpered together.
Do not start the engine.
Turn the key to the on position.
Count the SYS light flashes.
First should be 1 flash folled by 2 flashes. That's code 12 and is the default code even if there are no stored error codes.
After THREE code 12's the next error code will be flashed THREE times.
Count the flashes for the first number. Count the flashes for the second number.
Flash.....Flash Flash = 12
Flash Flash ...... Flash Flash Flash Flash = 24
After all the stored error codes are flashed THREE times the ECM will start over and flash 12 THREE time and the sequence just repeats itself.
It's crude but it works and it's cheap.
Use a paper clip to connect A & B together.
IIRC it doesn't work if you ground A & B. It may but the procedure calls for A & B to be jumpered together.
Do not start the engine.
Turn the key to the on position.
Count the SYS light flashes.
First should be 1 flash folled by 2 flashes. That's code 12 and is the default code even if there are no stored error codes.
After THREE code 12's the next error code will be flashed THREE times.
Count the flashes for the first number. Count the flashes for the second number.
Flash.....Flash Flash = 12
Flash Flash ...... Flash Flash Flash Flash = 24
After all the stored error codes are flashed THREE times the ECM will start over and flash 12 THREE time and the sequence just repeats itself.
It's crude but it works and it's cheap.
