91 c1500 ABS problem

[nick hand]

I have a 91 sportside pickup that has a mechanical thump sound coming from the rear when I come to a stop using full braking when I start to take off again. My rear brakes and drums have been replaced. It does not happen when I slowly come to a stop. It feels like my brakes are not releasing when I remove my foot from the brake pedal. I also have a light that is dimly light on the dash showing the word brake. I pulled the fuse for it and it goes away but comes back in a week or so. I don't know if the problems are related but suspect not. My mechanic can't seem to find the problem. Any suggestions would be appreciated.

 

[Erik the Awful]

The driveshafts are pretty notorious for clunking when you release the brake pedal. The solution is to take the rear u-joint loose and work the driveshaft forward and back on the splines to clean up any schmoo.

As for the light, is your brake master cylinder full?

 

[nick hand]

Yes the master cylinder is full and replaced. I will try the driveshaft synario. Thanks.

 

[Schurkey]

I also have a light that is dimly light on the dash showing the word brake.

I just checked my '97 service manual. The "BRAKE" light can be triggered by the safety switch in the combination valve, the park brake pedal switch, or the ABS.

Your earlier truck may or may not be different. I'm sure the park brake switch and the safety switch will each trigger the light. I don't know about the ABS.

I read somewhere--but NOT in my '97 manual--that the park brake switch makes the light glow at half-brightness, while the safety switch turns it on full-brightness.

Common for the park brake cables to get stiff and not return to position; which makes the park brake pedal droopy, which means the park brake pedal switch stays on. Therefore the BRAKE light stays on--at half-brightness.

 

[OlSmokie]

Yes the master cylinder is full and replaced. I will try the driveshaft synario. Thanks.

Like Eric said, it is most likely the driveshaft. Mine did the same thing until I undid it from the rear end, slid it right out of the transmission and put a very light coat of grease both inside on the splines and outside on the yoke. Problem gone.