Mechanics

ANTI-LOCK BRAKE LIGHT ON-WHAT ARE COMMON CAUSES

1996 Buick Century • 80,000 miles

Anti-lock brake light stays on
Avatar
Rlcfcs@sbcglobal.net
February 12, 2012.



Very well could be abs sensor

Tiny
Barrymerrell
Feb 12, 2012.
Where is abs sensor

Wheel speed sensor or abs module/sensor. Have it scanned for codes and let us know what they find.

Rivermikerat
Feb 12, 2012.
Your car doesn't seem to have ABS sensors, just wheel speed sensors at the wheels.

Rivermikerat
Feb 12, 2012.
You need a mechanic. When the warning light has turned on, a diagnostic fault code has been stored in the ABS Computer. That code will lead to the circuit or system that requires further diagnosis.

The most common cause on your car is a front wheel bearing. General Motors loves to design cars with very expensive assemblies. That saves them time and money on the assembly line but often makes repair parts for their cars very expensive. The front wheel bearings develop a little looseness, which is common and normal, but since they build the wheel speed sensors into the bearing as an assembly, that looseness allows the speed signal to drop out and make it look like that wheel has locked up. Since this happens when you are not pressing the brake pedal, the computer knows the wheel has not really locked up and that missing signal is a problem, hence the warning light.

That bearing wear often causes a problem in as little as 15,000 miles. The dealers' scrap metal bins are full of old bearing assemblies. There are other possible causes for the warning light being on, and that's why having the code read is the place to start. Be aware too that some ABS Computers can only store one code at a time and some computers will not test other things while driving when something it compares it to has a code already set in memory. That means your mechanic might read the one stored code, give you an estimate for repair, perform the repair, THEN a different problem will be detected and set in memory and you have to start all over again. That can result in a lot of frustration, the assumption the mechanic didn't fix it right the first time, the assumption the mechanic doesn't know what he's doing, or the assumption he's trying to rip you off. In reality, he is just as frustrated as you are. The chance of that happening is very small if you take the car in for service right away before any second problem has chance to occur. People run into this more often when they wait months or years to get the problem fixed. That gives a lot of time for a different problem to pop up.

Caradiodoc
Feb 12, 2012.
Cardiodoc, they can have it scanned and do most of the work themselves and save a pretty penny in labor. They'll just have to take components to a good machine shop to have the bearings pressed in and out.

Taking it to a mechanic is easier, and doesn't get you all dirty and greasy, with bloody knuckles, but you'll save several hundred dollars in the process. And you can get a temporary subscription to a pro reference source right here:
http://www.2carpros.com/articles/mitchell1eautorepair-car-repair-manuals

cardiodoc is exactly correct about the frustration level with a fault like this. Doing the work yourself gets rid of the "he's trying to rip me off" frustration and the frustration of paying an arm and a leg for labor. And the recurring "Now we found this problem" phone calls from the shop.

Rivermikerat
Feb 12, 2012.
The reason my mind went straight to the "you need a mechanic" comment is when rlcfcs's comment about "where is it?" Now we know we're in a conversation with a do-it-yourselfer who, like most people, doesn't know how ABS systems work, but would like to learn enough to be able to at least diagnose the problem.

You know how long-winded I can get, but in this case, I'd wear my fingerprints off from typing everything rlcfcs would need to learn. I'll gladly do that if the interest is there and I'm asked.

Caradiodoc
Feb 12, 2012.
The poster likely doesn't have access to the equipment required to read the computer anyway and I doubt the parts store will be much help either in this case. That brings you back to the mechanic.

Wrenchtech
Feb 12, 2012.
True on both accounts, but with the subscription, all the information needed to test the systems is there. The scantool can usually be rented or borrowed. And, if need be, here's a relatively inexpensive scantool from Amazon:
http://www.amazon.com/Autel-MaxiScan-MS409-OBD-II-Scanner/dp/B001LHW9YG/ref=pd_sbs_auto_7

I don't like telling people to take their cars to a mechanic, unless it's something really deep and troubling. Most everything the average person that knows how to read can do, with the right help and the right tools. We're the right help part. Most parts stores can help supply the right tools, either rented or borrowed/loaned.

Rivermikerat
Feb 12, 2012.
The tool that you posted a link to, much like the tools AutoZone uses are nothing but generic code readers and won't do a thing for ABS. The poster needs a professional scan tool and then will needs some professional technical knowledge and possibly a lab scope. Definitely out of his league.

Wrenchtech
Feb 12, 2012.