# 1990 Chevy C1500 brake problem



## Rattletrap (Sep 26, 2011)

Hi Folks, new to this forum, so hopefully someone can help point me into the right direction. My PU recently started acting up when I would press on the brake, the pedal would apply the brakes, and the longer I kept my foot on the pedal, it would bounce 3 or 4 times with a weird noise, but would stop the truck. Fluid reservoir is full. Truck is Silverado, engine is 5.7 with AT. Any ideas? :4-dontkno


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## Troy_Jollimore (Dec 31, 2007)

My father has a '93, which has ABS to the rear wheels. This could cause the pulsation or 'bouncing' that you're feeling. The control module or other part of the system could be faulty. BTW, we're in a bad spot for rust, but I'd advice double-checking your front disc calipers and rear drums if you can. Make sure nothing's seized.


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## Rattletrap (Sep 26, 2011)

Thanks Troy, I'll look into those areas. One thing that I do recall, the brake light came on and then the brakes worked perfectly for some time. Then, I had to replace the alternator. After replacing that, the brake light stayed off, but the brake problem came back, making me think the problem is electrical in some way. A friend gave me a working control module, but that didn't help.


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## kjms1 (Jun 4, 2010)

you need to see if you can pull any codes out of ABS system

when you say bounce was the brake pedal pulsing


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## Basementgeek (Feb 7, 2005)

if this only happening a slow speeds like 10 MPH and under probably ABS problem. 
Pull the fuse to ABS to check, so I have been told.

BG


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## Troy_Jollimore (Dec 31, 2007)

When the warning light was on, the control module had probably disabled the ABS system, which is why your brakes were working fine. I'm not sure how it reset with just a new alternator (unless your battery was disconnected), but it's probably trying to work the system with faulty data from itself, or one or more of the sensors. As was just mentioned, pulling the fuse might amount to the same thing.

Getting the codes would be nice, but you'd probably have to see a dealer for that on a pre-OBDII vehicle.


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## Rattletrap (Sep 26, 2011)

I pulled the fuse to the ABS system and disabled it. The brakes work fine now without pulsating, so now I know the problem is in the ABS system. I'll have a mechanic check that out and correct the malfuction. Thanks for all the input, that was a big help.


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## Basementgeek (Feb 7, 2005)

Glad you were able to narrow it down.

BG


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