My 95 3500 has a brake problem. Whenever I back up the brake pedal is firm and the brakes don't stop very well. When I first purchased this truck in May the pedal was soft and would go the the floor if you held it firm. I replaced the front pads, rear shoes 1 rear wheel cylinder and master cylinder. The soft pedal is gone but I still have the backing up brake problem. Now the dash "brake" and "abs" lights come on when I stop then go off after I start moving again. After I rebuilt the brakes both of the aformentoned brake lights would stay on all the time. The only way I cured this was to unplug the ABS module under the dash. This new problem started just this week. Does anyone have any ideas.
I see by searching posts that alot of you guys have brake problems.
If anyone can help it would be appreciated.

 

Could be a faulty ABS module. It's forcing the brake pedal back and relieving brake line pressure, but it's not suppose to do it until it senses a locked up axle.

 

Do you have 2 or 4 wheel ABS?


Chris

 

It is rear wheel ABS.

 

One thing I have noticed about the pre-97 trucks, is that the ABS and brake light will come on when there is insufficient vacuum to the brake booster. When the vacuum comes back up to a sufficient level the lights will turn off. While I seldom trigger this while my truck is running, when I first start it, I can feel the brake pedal getting "softer" as it builds vacuum to the booster, then the lights go off.
Of course this is not the only thing that will make those lights come one, but that's the reason I see them most.
So, with your problem, if it is a vacuum level too low, you may have a leak in your brake booster that only shows up when you engage the brakes.
I'd check this by coming to a stop, where you said the lights would come on, and put it in neutral so I could release the brake pedal, and see if the lights go off.
Other symptoms of a vacuum problem are the vents in the dash. Does the HVAC system work properly, air coming out where it is supposed to, when the brake lights are on? This is not an absolute indicator, but may hint to a weak vacuum pump on the engine.

Chris