ABS sensor

[Andizzle]

Hello all. This is my first post. I just want to know where the ABS senser is located. My ABS light keeps on comin on. I was told to try and back up a foot and stop really hard. Try it about 6 or 7 times and that should adjust your rear brakes. Is that true? I have a 1994 grand AM if that helps. Please I need some advice ASAP. Thank you in advance.

[gagt98driver]

The ABS light will not be fixed by adjusting your rear brakes.

And yes its true that you can adjust the rear brakes on a GM vehicle equipped with rear drums by using the back up quick and stop hard method, but it takes more than a foot to adjust them. You need to get going at least about 10mph in reverse and then stop very firmly to get them to adjust.

However, with you having done it 6 or 7 times, you may have "over adjusted" the brake shoes to the point that they are now constantly dragging on the drum. You should only to the "back up adjust" at the most 2 times in a row or you can "over adjust" as I just mentioned.

I would suggest taking the car in to have codes read as to exactly what is tripping the ABS light - possible faulty sensor or possible problem with the actual ABS control units.

Secondly I would suggest you jack up the rear of your vehicle, place it on blocks (which should be easy since it should have a solid rear axel) and pull both wheels and brake drums off. There should be an adjustment mechanism you can see after you remove the drums (which btw should simply slide off the rear lugs once the wheel is off).

The best way to set the rear shoes properly (and the way I've always done it when doing brake jobs on a rear-drum vehicle) is adjust the pads incrementally to the point that when you put the drum back on and spin the drum there is a slight drag on the drum.

Once you get to this point (the slight drag) remove the drum and adjust the shoes in small increments until you no longer have any drag on the drum.

[Matt95GT]

When does the ABS light come on?
-right after engine start?
-after driving?
-hard stops?
-at a certain speed?

The front ABS sensors are behind the rotor. Turn the steering wheel all to one side, look for the teeth on near the CV boot. The sensor is mounted on a small black plastic wedge-shaped piece.

The rear sensors are part of the drum assembly.

The preceedure you mention will self-adjust the rear drums, but has nothing to do with ABS.

Try to look for a pattern. For example... the ABS light comes on and stays lit whenever I go over 70 MPH. In my case, it's not the sensor (replaced already) It must be an inprefection in the toothed wheel... has been doing it ever since I got a CV shaft from AutoZone. :roll2:

[Andizzle]

Right on Buddy thank you for your help.

[Andizzle]

It came on this morning when I was cruisin at about 70. But yesterday it came on when I was in Traffic. Do you think I might need to just adjust the rear brakes or change the sensor?

[LargeFish]

ABS diagnosis in service manual is a huge section. Scanner best place to start unless you can spot something obvious, like a disconnected sensor. Could also be flakey dash maybe...

[Andizzle]

Is there any way I can get that ABS section e-mailed to me. When i bought the car it didn't come with a service manual. So I'm kinda S.O.L.!!

My Email addy is AndyS@ELoan.Com

[LargeFish]

No cars come with service manuals. You can search around the site for some web based ones like: http://www.gaownersclub.com/forum/showthread.php?postid=253973 but you can't do ABS diagnosis without a scanner anyways...

[Andizzle]

Yeah I have a scanner to use........... I'm checking that website right now. Thank you!

[Andizzle]

I just tried it and "It cannot connect to server" Then I read in one of the other forums that it doesn't work anymore. Anymore suggestions. I have a scanner, actually my buddy does, and were gonna check it out on Saturday. Any other website suggestions??? as far as info on what to do??? or diagrams I can print out?

[LargeFish]

It's a special scanner for the ABS system that you will need AFAIK. The Haynes and Chilton manuals don't reccomend the home mechanic working on the ABS system due to the complexity. Another thing you might try for a shop manual is the public library... There are several different links in the service manual thread also...