Low brake pedal

Maintenance/Repairs
1

2002 Chevy 1500 - Had the rear brake done, changed the rotors and pads and bleed the system, however the brake still goes to the floor. The truck stops but the pedal is low. How do you fix this?

2

@‌BigB

If you’ve had the brakes bled, then you might have a bad (bypassing) brake master cylinder

I certainly hope the shop didn’t hand you back the truck with that sinking brake pedal, and say everything’s fine

I don’t know if the shop said all that work would fix the sinking brake pedal . . . but they definitely missed something

Since “the brake still goes to the floor” I assume that is the reason why you brought the truck to these guys in the first place. And they apparently didn’t resolve your initial complaint

3

Either there is still air in the system or more likely bad master cylinder.

4

How are the brakes configured? Front disc, rear drums? If so, maybe they haven’t adjusted one or both of the rear shoes so they are close to the drums. There’s a manual adjustment required, and sometimes a shop tech can forget to do it. Or they do it, but after you drive a bit, things move around, and it has to be done again.

If it is configured discs all around, those usually don’t require any manual adjustment. But a low pedal could be any of a number of problems, first guess, there’s still air remaining that needs to be bled out again; one or more rubber brake hoses need replacement, have someone press on the pedal while you look at the hoses one by one, see if you notice anything unusual, like one of them expanding, or moving in a weird way; possibly the master cylinder seals were damaged during the prior bleeding, which is not an uncommon thing, especially if they don’t use a pressure bleeder and just use the “press the pedal to the floor” technique.

Edit: You don’t say if you have ABS, but if so, that system can require special treatment. On some ABS systems, a special scan tool is required to effect a proper system bleed operation.

I expect this will prove easy to fix, but just requires some patience as you or the tech goes through the possibilities one by one.