Antilock light on my 87
Thread Starter
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Antilock light on my 87
Noticed a few times lately that the antilock light comes on when I hit a bump in the road. Usually takes a good hit like a pothole and not just small bumps. The light goes out after an ignition switch cycle.
I don't think that the early C4's store any codes as history information in the ECM so the only way to find a error code is when the light comes on. I have access to a Tech-1 at work but that's typically not when the light comes on.
Is this something that may be due to a loose wire or connection? Maybe a bad VSS at one of the wheels? Bad ABS control module relay or possibly the accelerometer?
The ABS works fine and I can hear the self-test every time the engine is started and the car moves thru 4 MPH just as it should.
I have seen the antilock light come on at some autocross events where the surface has a few bumps. Fluid level is fine and I bleed the brakes before each autocross and track day. No signs of fluid leaks anywhere.
Ideas??
I don't think that the early C4's store any codes as history information in the ECM so the only way to find a error code is when the light comes on. I have access to a Tech-1 at work but that's typically not when the light comes on.
Is this something that may be due to a loose wire or connection? Maybe a bad VSS at one of the wheels? Bad ABS control module relay or possibly the accelerometer?
The ABS works fine and I can hear the self-test every time the engine is started and the car moves thru 4 MPH just as it should.
I have seen the antilock light come on at some autocross events where the surface has a few bumps. Fluid level is fine and I bleed the brakes before each autocross and track day. No signs of fluid leaks anywhere.
Ideas??
Race Director
Joined: Sep 2003
Posts: 16,838
Likes: 341
From: Database Error Indiana
Sounds like a wheel bearing getting some play in it. The gap at the sensor can change when you hit a bump and trigger the light. May be other possibilities but this is my first choice.
