philipjohn52

I have a 2000 Chevy Express 3500 with a VanLadder unit installed on the roof. I have it parked behind my house on a flat surface where I've been using it the past year to install new siding. I have to repair it where it currently sits as moving it without brakes is not an option. Last week, when I got in it to move it a few feet forward, I released the parking brake, first noticing that the red "Brake" light on the upper left of the dash stayed lit. Then, when I pressed on the brake pedal before putting it into Drive the pedal went down to the floor. Using tire chucks separated by 3 feet front and back, I put it in gear and tried to move and stop. The truck stops only when the pedal bottoms out on the floor. Assuming it was a bad master cylinder, I bought a new one, bench bled it and installed it yesterday, but did not bleed the system yet. I expected to have SOME pedal when I got in and started it up, but I get the same down to the floor pedal action. The fluid level in the old master cylinder was to the top, and there was only a little crystallizing fluid at the back of the piston, with the Hydra-boostr chamber relatively clean. A quick look at the area of the four wheels does not reveal any leaking brake fluid, nor are there any indications of a leak in a line/hose.

I've read elsewhere online about the possibility that the problem could be caused by faulty ABS sensors, check valve, proportioning valve, booster unit or pressure modulator valve.

The "Check Engine Light" light has occasionally come on but has disappeared within a few hours of truck use, and right now it is not lit. I do have an OBDII bluetooth unit that I just bought but haven't used yet. Is there something that hooking that up will reveal? Or is there something else that is likely the primary culprit, or are there other tests I can perform that will isolate the problem?


PLEASE HELP!!!