Brake Problems

[RandyW]

I recently replaced my brake master cylinder because the back brakes were not getting any fluid. Now when I'm driving I can apply the brakes and everything is find UNLESS I let off the brakes and apply them again and everything is fine but the third time I have no brakes and the red "Brake" light and the amber "ABS" light come on. Appreciate the help with this one.
BTW my truck is a 1994 DRW 3500 with 200,000 on the odometer and 5 sp manual transmission.

 

[GAmes]

A common problem with a vacuum booster. Check the system for leaks.

 

[B.G. Smith]

Would the loss of vacuum turn the ABS and brake light on?

 

[GAmes]

The ABS has a low vacuum sensor that will trigger the light. If the '94 is like my '97 the brake light illuminate whenever the ABS light is on.

 

[RandyW]

Thanks everyone. I'm not sure how to check the vacuum booster but I'll be looking into it.

 

[B.G. Smith]

Probably first you need to check and see if your vacuum pump is doing what it is supposed to do. To do that you need to connect a vac. gauge to the inlet of the vac. pump and run engine, check vac. I have read that you can get by with as low as 17" but 23" or higher would be better. If the pump is working, run engine a couple of minutes and shut off. Press brake pedal, you should get vac. assist for a couple of presses. If you don't get assist then either the booster is bad or the check valve is not working. They used to install the check valve in the rubber connection where the vac. hose connects to the booster. bg