i bought my truck on friday and i knew it needed brake work. thats how i got it so cheap. anyways, the brake light was on and the pedal was on the floor but the truck stopped ok. i replaced the rear shoes along with a new spring kit for it and i noticed it had a new wheel cylinder on the right side. i also replaced the front pads. after doing the rear brakes, i bled them just to make sure there was no air. all i got was fluid. im stumped. after putting new shoes and pads on, the pedal is still low. after i first did the brakes, the brake light would only come on after a hard stop, like the fluid was low. but i filled the master. but now it is on constantly. i thought i had the rear brakes adjusted. could it be possible i didn't adjust them enough or is there something else im missing? it does have abs, and that light is on too. could that have something to do with it? thanks in advanced.

 

Take it to a brake shop/dealer. Your problem is in the [B]rake [P]ressure [M]odulator [V]alve that has a bleeding procedure and if you don't get it right the ABS not going to work right until that is fixed. It requires the Tech1 scan tool to fix properly? I have the GM Service DVD and the information there tells me that unless you are good at bleeding and fixing the ABS then I would let the "Pros" handle it...unless you have an older GM Tech1 scan tool.

You might need a new one if the pedal still goes to the floor.

 

The most common problem that I have seen with a low brake pedal on a system with rear drum brakes is the adjustment.
To make sure the rear brakes are properly adjusted.
Start by making sure thet there is slack in the parking brake cable.
Then adjust the shoes close to the drums. I adjust the shoes a little, then put the drum on. If it goes on easy, I pull the drum off and adjust the shoes a little more. Repeat this until there is a very slight drag when putting on the drum.
I'm not talking tight so you need to hammer it on, just a slight drag.
Then when both drums are on, feel the brake pedal. If it's up high, then you can adjust the parking brake cable.
With both wheels off the ground, trans in neutral, you should be able to spin the wheels by hand. If that's ok, push the park brake on til the ratchett clicks about 4 times. Now adjust the cable to the point where you can't turn the whells by hand. Release the park brake cable and make sure the wheels spin free again.

Try that first before you start replacing parts.
If it doesn't work, repost with an update....hell, post an update anyway.

 

He should not have to remove the drums to adjust the rear drums, if they are anything like past drum brakes there should be a slot at the bottom of the backing plate with a rubber plug in it, remove the rubber plug and he should be able to get to the adjuster with a flat blade screw driver or purchase an adjuster at the local Auto parts store.

But from what I saw in his initial post his ABS light is on and I read the procedure for bleeding the brakes in the GM Service DVD and it mentioned the Brake Pressure Modulator Valve and if it had air in it from being replaced or other reason then it needs to be bled before doing the brakes since if it contains air in it then it could lead to a low pedal situation...

 

after i did the brakes on it i pumped the pedal without it running and it didn't stay hard like it should. i sank a little like ther was air in the lines. when i go have the truck inspected, i will have them check it out. nys is a bear for inspections..worse if a vehicle is a '96 or later.

 

master cylinder maybe...it can leak back past the piston causing brake pedal to keep going down while still braking you somewhat.

 

By far the easiest way to adjust rear drums is to back up and put the brakes on. They self adjust when you back up with the brakes on. That's why you dont own a circular driveway.

Typically the brake light comes on when you have a fluid leak, or are low on fluid, or the e-brake is slightly applied (only takes on little bump of the foot).
Typically the ABS light comes on to tell you there is a fualt in the ABS system and they have been deactivated. The fualt could be low fluid, more then likely it is a dirty sensor. I don't remember waht year your is, however its more then likely the front sensor. You can get hte codes pulled for the ABS system to be sure what hte trouble is.

 

Good point by magnum434, it could be a master cylinder.
If you take off the 2 mounting bolts and slide the master cylinder forward, you can check for a fluid leak at the back of the master cylinder.
I must have bad eyes,because I didn't read anywhere in your post about an ABS warning light on, only a brake light. Could you clear that up for me?

If you pump up the brake pedal, does it get hard then slowly go down to the floor? If it does, it sounds like a faulty master cylinder.
post up, I'm curious.

 

yes..both the abs and brake light are on. and when i do pump it it sinks a little, but dosn't go all the way to the floor. if i have time tomarrow before i head to work i will check behind the master to see if it's leaking. i havn't really driven it since tuesday cause it isn't totally 'legal' yet.

 

hey about the ABS...someone said a dirty sensor....tell me how to clean it....because mine is on constantly and im 99% sure its not pads, rotors, etc. I think it's the ABS actuator which would be freakin expensive...so yea...I'm up for saving $500 if it is just a dirty sensor...How i clean it?