1994 Chevrolet Cavalier Braking Issue

chevrolet

#1

I have had this issue with the braking system for about a year now. Most of the time when using the brakes, everything works fine, but once in awhile, it seems like the brakes on one (I think one) wheel seem to just let go, apply full braking power, or both one after the other. When this happens, you hear loud clunking sounds (which I guess it the caliper going from on to full off and back again) and the rear of the car will raise and lower with the instances. There are also times when a high pitched squeak sound comes from the wheel (like when a bus uses their brakes) which will normally happen a second before coming to a full stop. It does not happen at the same time, but I think is related. Going off the sounds and rear of the car moving I tend to think this is focusing around the driver’s rear tire. The brake fluid has been changed, the brakes have been changed on all 4 wheels, and so have the all brake lines to the cylinders. There are no leaks anywhere in the system. The car does have ABS.

This has now stumped me. Has anyone else dealt with an issue similar to this and figured out what the issue is? Anyone have any ideas? I am open to suggestions for repair.

Thank you in advance!


#2

I’m not an expert, but I think there is a fuse you can pull to disable the ABS. If you do that you can verify or eliminate it as the source of the problem.


#3

Hmmm… Well there’s a thought. I will give that a shot and reply.


#4

Update. There is a fuse, but it also runs coolant fan, HVAC, Heater, A/C Power, DRL Module, Starter, and Charging System. I could live with pulling the fuse if it wasn’t for the coolant fan, starter and charging system.


#5

Im a bit confused… you will surely know if the ABS is coming into play here…you either feel it or you dont…its not very subtle.

You should not be experiencing any ABS action unless the ecu detects wheel lockup…like I said…its not subtle.

Aside from that I think you are trying to describe a semi locking caliper and its after effects. Hard to say from here.

Blackbird


#6

It happens during normal driving conditions, dry pavement, light or heavy pedal. Just happens when it feels like it.

I am wondering if it is a sensor that has gone haywire and it detects wheel lockup when there isn’t.

One more thing I forgot, after it happens, and I take my foot off the brake, and go to accelerate from the stop, there is about two clicks that happen from under the hood. Only happens after this issue.

I was thinking it has to do with the ABS somewhere, either with the module under the hood or a sensor of some sort at the wheel. It is DEFINITELY not a subtle thing at all when it happens. I just am not sure what all could cause that issue.


#7

Unplug one wheel speed sensor. That should error-out the ABS and cause it not to function. See if your problem goes away. If it does, leave the thing unplugged and ignore the light.


#8

I can give that a shot. I’ll try with the wheel that has the issue.


#9

Your car has 3-channel ABS, so both rear brakes should be affected equally by ABS action.
See if this applies: Under the hood, on the driver’s side of the blower motor sticking out of the fire wall, there should be a single relay in a holder pointing upward. This should be the ABS Enable Relay. Try pulling this. (On the other side of the blower should be a gang of relays: A/C Compressor, Radiator Fan, Fuel Pump, and Blower…obviously, don’t touch these.)


#10

Could be the ABS, definitely worthwhile to adopt the ideas above to disable the ABS and see what effect it has. But with the symptoms you report I guess there’s something more serious going on, like a caliper is locking up or a flexible brake hose is collapsing. Master cylinder, power booster, or a parking brake problem are other possibilities, but unlikely. If you have rear drum brakes, those can lock up too. First off, you need a brake expert to inspect the calipers, make sure they are sliding along the guide rails smoothly, and that the caliper pistons move in and out freely. There’s a similar test for rear drums if you have those.


#11

Just a quick update. Pulled the ABS Enable Relay under the hood 5 days ago. That solved the problem entirely. I want to wait to make sure the issue never came back before I posted and it has not. Thank you everyone!


#12

Thanks for the update…it is appreciated.


#13

I expect you already know, but you’ve disabled the ABS system. Shouldn’t be a problem provided you are willing to live without the decreased stopping distance ABS affords in emergency stops. This is a good time to drive a little slower, just to be safe.


#14

Yep. I figured that’s what I did. I don’t think I ever set off the ABS anyway when it actually worked. Driven many a car before ABS existed. And at least it’ll come to a stop now instead of just deciding to let go of the rear wheel brakes.

Still driving around and still have never had an issue since.