ABS/Brake issue

ELTON AND LAURA FAN

MEMBER
2001 BUICK CENTURY
169,000 MILES

I have a 2001 Buick Century Custom and my friend has a 2002 - same problem.

The ABS and TRAC OFF lights are on and sometimes when the brakes are applied, there is a "motor running" sound with vibration in the pedal and loss of braking. Pulling the ABS fuse remedies the sound, vibration and they brake normally, but then the BRAKE light is on in addition to the others.

In mine, both wheel bearings have been replaced, all brakes replaced, hers, all brakes replaced and one of the wheel bearings.

Two days ago, I had a problem with it not starting, thought it was the starter, but the mechanic told me it was a "wiring problem" and that he fixed it. I don't know what he did, but it does start and now just the ABS and BRAKE lights are on, the TRAC OFF light is off.

I am thoroughly stumped. Please help!

1 Reply

CARADIODOC

MECHANIC
33,761 POSTS

First have the diagnostic fault code(s) read. Those will indicate the circuit or system that needs further diagnosis.

GM has a huge problem with wheel bearings. Due to their poor design, the wheel speed sensors develop really wimpy signals to start with. Then the wheel bearings develop a little play, which is normal, but that play lets the signals get even weaker until they drop out and can't be seen by the computer. To the computer it looks like that wheel has stopped rotating so the traction control kicks in to slow the other wheel, or if you have the brakes applied it will activate the anti-lock function. That's the vibration and buzzing you're feeling.

New wheel bearings can develop the same problem in as little as 15,000 miles. The dealer's scrap metal bins are full of these bearings.

Your mechanic can also drive the car with a scanner connected to view the wheel speed data. It will show if and when a signal drops out. Be aware too that there are some aftermarket scanners that have a software problem that confuses two of the wheels. As I recall, it will incorrectly list a fault code as being for the right front wheel instead of the one that actually has the problem. Sorry I can't remember the exact wheels and the brand of scanner.