Mechanics

ABS

1996 Pontiac Grand Am • 4 cylinder 2WD Automatic • 198,000 miles

My abs light comes on sometimes I had it diagnosed the dealer said nothing is wrong with the abs sometimes when I put on brakes the car pulsates and acts like it doesnt waqnt to stop what could this be
Avatar
Peanutsaregood
July 24, 2011.




Once the light comes on there is a diagnostic fault code stored in the computer. How can they say nothing's wrong when they have a code to look at? The most common problem on GM front-wheel-drive cars has been the front wheel bearings. They are not defective or worn out, but they develop enough normal play that the signals drop out from the wheel speed sensors. That makes it look to the computer like that wheel is locking up. GM likes to build those sensors into the bearing assemblies so you have to buy more parts. Funny thing is that bearing is less expensive with the sensor than the exact same bearing without the sensor.

Another common problem occurs if you let this one go for a while. A second problem can develop, typically the other wheel bearing, but it won't set its own fault code because with the first code already set, the computer can't use that erroneous signal to compare other wheel speeds to it. That causes the light to turn on and the new code to set right after having the first problem fixed. A lot of people blame the mechanic for not diagnosing or fixing the problem correctly when the real cause was two different problems but only one set a fault code.

Caradiodoc
Jul 24, 2011.
Thank you always get great knowledge on this web site keep up the good work
AD

Tiny
Peanutsaregood
Jul 24, 2011.

AD