Service ABS
Thread Starter
Intermediate
Joined: Mar 2010
Posts: 32
Likes: 0
From: San Antonio Texas
Service ABS
I took my 1990 Corvette to have the air conditioning checked cause the compressor would not engage. I was told the computer was bad cause it wasn't grounding or something to that effect. The computer was replace and the air came on an worked fine. However, when I left the shop, the service abs light flickered and then stayed on. Also, I could no longer hear the pump come on. Before I take it back to the shop, is there any suggestions on what could have happened. Thanks
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 42
From: Baltimore, MD USA
Take a piece of wire and short Pin A which is Ground to Pin H on the diagnostic connector above the drivers right knee.
Turn the Ignition On. After 3 seconds, any DTC's will flash using the Service ABS lamp.
Code 12 will flash three times, any Trouble codes 3 times then code 12 again three times. Example 12 would be a flash pause flash, flash long pause then next code.
12 Diagnostic System Operational.
21 RF Wheel sensor fault
22 RF Sensor frequency error
25 LF Wheel sensor fault
26 LF Sensor frequency error
31 RR Wheel sensor fault
32 RR Sensor frequency error
35 LR Wheel sensor fault
36 LR Sensor frequency error
41 RF Solenoid valve fault
45 LF Solenoid valve fault
55 Rear Solenoid valve fault
61 Pump motor or Motor relay fault
63 Solenoid Valve relay fault
71 EBCM fault
72 Serial data link fault
75 Lateral accelerometer fault Short to B+ or Ground or Open circuit.
76 Lateral accelerometer fault. Signal out of range or incorrect.
To clear codes. (May take a couple of tries because the method is very primitive). Hooking up a momentary switch between Pin A to Pin H
makes the process easier.
Jump Pin A to Pin H
Turn ignition On
Wait for codes to begin flashing
Remove jumper from Pin H
Ground Pin H for one second then remove the jumper.
Ground Pin H for one second then remove the jumper.
Ground Pin H for one second then remove the jumper.
(This must be done three times within 10 seconds).
Reconnect jumper and wait at least 15 seconds.
Turn ignition OFF
Jump Pin H to Pin A
Turn ignition On
Verify code 12 is the only code flashed. If not, either the code
clearing procedure was not completed correctly or there are still
ABS system faults.
Turn the Ignition On. After 3 seconds, any DTC's will flash using the Service ABS lamp.
Code 12 will flash three times, any Trouble codes 3 times then code 12 again three times. Example 12 would be a flash pause flash, flash long pause then next code.
12 Diagnostic System Operational.
21 RF Wheel sensor fault
22 RF Sensor frequency error
25 LF Wheel sensor fault
26 LF Sensor frequency error
31 RR Wheel sensor fault
32 RR Sensor frequency error
35 LR Wheel sensor fault
36 LR Sensor frequency error
41 RF Solenoid valve fault
45 LF Solenoid valve fault
55 Rear Solenoid valve fault
61 Pump motor or Motor relay fault
63 Solenoid Valve relay fault
71 EBCM fault
72 Serial data link fault
75 Lateral accelerometer fault Short to B+ or Ground or Open circuit.
76 Lateral accelerometer fault. Signal out of range or incorrect.
To clear codes. (May take a couple of tries because the method is very primitive). Hooking up a momentary switch between Pin A to Pin H
makes the process easier.
Jump Pin A to Pin H
Turn ignition On
Wait for codes to begin flashing
Remove jumper from Pin H
Ground Pin H for one second then remove the jumper.
Ground Pin H for one second then remove the jumper.
Ground Pin H for one second then remove the jumper.
(This must be done three times within 10 seconds).
Reconnect jumper and wait at least 15 seconds.
Turn ignition OFF
Jump Pin H to Pin A
Turn ignition On
Verify code 12 is the only code flashed. If not, either the code
clearing procedure was not completed correctly or there are still
ABS system faults.
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 99
From: Ashland PA
2021 C4 of the Year - Modified Finalist
You may want to check out this link for reading your codes on a 1990 C4. This link will show you how to flash ABS codes. It will also show you how to display codes digitally on the dash.
http://corvettephotographs.com/c4vettes/codes.htm
http://corvettephotographs.com/c4vettes/codes.htm
Last edited by eutu1984; Feb 11, 2013 at 08:07 AM.
