Brake system problems - any experts?

kaysee · 04-22-2002, 03:17 PM

Help!

On the way back from work, my brakes decided to start misbehaving. I've been on a couple of test drives, but still don't know what's going on. Anyone got any ideas?

Symptoms:

The problem occurs occasionally, only at slow <20mph speed. You press the pedal down, and a clicking\crunching noise comes from under the hood. When this happens, the brakes work at about 15% efficiency - enough to be scary. They feel very odd when doing this - they catch, and then release, but seemingly at random. The whole time, the strange noise is coming from somewhere.

Most of the time, however, the brakes work fine, no problems at all.

discs and pads are fine, the noise is definately coming from the engine bay, but it's hard to tell exactly where.

Car is FWD, with ABS.

A couple of times, the ABS light has come on and stayed on - could it be an ABS problem?

Maveric · 04-22-2002, 03:22 PM

Sounds like it could be bad rotors. You definatly should have it looked at.

PS This should be in the off-topic section.

mp3z24 · 04-22-2002, 03:26 PM

can you feel the pedal vibrating or pushing back on your foot... that would be the ABS kicking in. if it is kicking in on dry pavement at low speeds there is definately a problem! if this is a car under warranty take it back and raise some hell! if it is NEW within a couple of days (2-3) take it back and ask for a new car. if it is older and out of warranty... invest in a scan tool. they are pretty cheap now-a-days, and you can get them at most (if not all) auto parts stores, and maybe even wally-world (wal-mart). you should have one of those anyway if you want to tell what is wrong with your car, especially if it is new. you should be able to pull the code and decifer what the computer is trying to tell you with the stupid blinking ABS light.

personally i hate dummy lights... they give you an oil warning light, but no oil temperature gauge. makes no sense to me... kinda like warning you after something goes wrong!!!

~mike

kaysee · 04-22-2002, 03:33 PM

Was undecided if this was off-topic or a general question... oops..

Car is out of waranty, so no luck there.

If I stamp on the brakes, I can lock the front wheels, so it's not the ABS working when it shouldn't - it feels nothing like ABS when it's bad. It's a very strange feeling.

Would bad rotors cause the under-the-hood clicking noises I'm getting? It's a loud, distinctive noise.

mp3z24 · 04-22-2002, 04:22 PM

ummmm stomping on the brakes in a car that has abs should NOT cause the brakes to lock up... only once have i had abs come on in my car on dry pavement and i totally stood on the brakes from about 50-0 mph in about 25 feet. gotta love people that pull out in front of you !!!

again. i say go and get the scan tool. if the wheels lock up when you brake super hard then your abs is not working. hard to diagnose without actually driving it

i interpret bad rotors as warped.... in which case you would feel a pulsing when you brake. kinda like the whole car is lightly pulsing when you stop. not like the normal abs feeling in the pedal only. the steering wheel would lightly pulse also...

get this checked out ASAP

~mike

kaysee · 04-22-2002, 04:28 PM

I don't see as it can be a warped anything - it's so intermittant, that I think it must be electrical. I've a feeling my ABS pump or relay must be shot.

Looks like i'm off to car-hospital tomorrow. fingers crossed it's an easy (ie, cheap) fix..

thanks for the help

DodgeCummins · 05-05-2002, 09:04 PM

There is a point where your ABS brakes will lock. It is pretty hard to do but it is there for a couple of reasons.

one you may have a problem and rather than have abs release all brakes it will allow lockups.

the second is the fact that at some point your wheels have to stop turning, if the abs never stopped then you could never park the car because the brakes would release completely upon stopping.

that means if you panic stop hard you could lock the brakes up.

kaysee · 05-06-2002, 05:45 AM

I've had the car looked at, and it turns out both my front wheel speed sensors are faulty. At slow speeds they were giving varying speeds, sometimes giving a 'wheel locked' signal.

The ABS was turning on, but because it only happened at slow speeds, they didn't quite function as they should.

I'm driving aroung now with the sensors unplugged - no ABS, but at least I can stop.

I just need to find a very large amount of money now to get the sensors replaced...