97 sierra brake problem

[TorqueWorks]

The brakes have worked fine, and recently I just started using the parking brake because i live on a hill, and no problems, but tonight on my way out I pushed to pedal to stop and nothing, I had to smash it to the floor to get any response from the brakes.

I turned around and came home and the whole way home, I would have to push the pedal past 3/4 of the way for it to work. After I push it all the way in, the pedal comes back up slowly. The parking brake light is now staying on aswell. I've pushed the parking brake on and it works still, but even when its off, the parking brake light says it's on (not usual).

I checked brake fluid in the plastic square container, and it was full. I also do not hear any grinding or shaking when I push on the pedal.

 

Anyone know what could be causing this sudden brake problem?

[TorqueWorks]

no one has an answer?

[94silverado4x4]

Yeah i am having the same problem ..

[TorqueWorks]

how long has it been happening to you?

[Mr. Smith]

If it has high miles I would look at the master cylinder.

[cajunairman]

If it has high miles I would look at the master cylinder.

 

<{POST_SNAPBACK}>

 

 

 

I had this same problem with a 1999 2500 Suburban with 99,000 miles on it. I completely flushed out the brake fluid with new fluid and the problem went away. I did also change to Stainless braided lines to replace the rubber ones but I don't think that was what was causing the mushy pedal. The old fluid was most likely the original and dirty as you know what. Hope this helps.

[Truckin2003]

on my 1997 with almost 154,000 miles on it the brakes were kind of spongy. i ended up just putting new pad and rotors on it and now its way better

[Z71-cummins]

im having the parking break light is on and wont go off and should i do the fluid flush would that get rid of the problem cause i have the spongy brakes also even after i got a brake job done.

[GMTRUCKTECH]

I HAVE SEEN THIS PROBLEM MANY TIMES ON THE 99 AND OLDER CLASSIC TRUCKS. ASSUMING YOU DON'T HAVE ANY EXTERNAL BRAKE FLUID LEAKS I.E. MASTER CYN OR WHEEL CYN AND YOUR PADS AND SHOES ARE IN GOOD ORDER, YOU MORE THEN LIKELY HAVE A INTERNAL BRAKE FLUID LEAK. TWO ITEMS THAT I HAVE SEEN CAUSE THIS AFFECT IS THE MASTER CYN INTERNAL SEAL BLOWN OR THE BPMV (BRAKE PRESSURE MODUALTOR VAVLE ASSM.) WHAT HAPPENS WITH THE BPMV IS ONE OF THE VAVLES INSIDE THE UNIT STICKS OPEN DUE TO OLD BRAKE FLUID OR BRAKE FLUID CONTAMATION CAUSING UNREGULATED FLUID TO BLOW BY. THE BEST WAY TO DIAG THIS IS WITH A TECH 2 DOING A FUCNTION TEST ON THE ABS, BUT IF YOU DON'T HAVE ONE HANDY DRIVE YOUR VEC AND SLAM ON THE BREAKS AND MAKE THE ABS SYTEM ENGAGE. BASICLY DO A PANIC STOP TO ENGAGE THE ABS FORCING THE BPMV TO CYCLE ITS VALVES HOPEFULLY FREEING UP THE STICKING ONE. YOU CAN TRY THIS MORE THEN ONCE. IF THIS WORKS FLUSH YOUR BRAKE FLUID AND YOU SHOULD BE GOOD TO GO IF NOT TRY A MASTER CYN. GOOD LUCK