Okay, I'm aware that a lot of people have posted threads about very similar issues before, and I hope this does not anger anyone, but I'm tired of searching the internet for "close to" answers. First, to start I will go ahead and say that I have a '01 1500 Ram V8, 5.2L RWD. Yesterday, I went ahead and changed out my front brake pads and skipped the bleeding. While I readjusted the pistons, I kept the brake line on, so I believe this pushed air into the MC, though I'm not sure. Anyway, come the following morning, I've bleed all the brake lines 10-20 times a piece, until I was certain there was no air in the lines. I kept the fluid topped off, and set up for a test drive. My brakes are still spongy, but after applying pressure, the brakes firm up. After leaving them for a few minutes, they they get spongy again, where I can press the pedal all the way to the floor. When I push on the brakes, the RPM drops about 100, and then raises again when I release. Finally, after pressing on the brakes a few times, the ABS and Brake light pop on. If I turn my truck off and turn her back on, the lights are gone. I'm seriously hoping that I will not have to replace the MC, but if that's the case, so be it. Any ideas before I do this?

 

Sounds like you have air in the abs module.

 

either that or you have a piston stuck in the caliper. had this happen on a old toyota truck i once had, almost caused me to drive it in a canal also.I would bleed the ever lovin' s**t out of them and if that doesn't work,Take each caliper off carefully. try not to move the pistons to much.you might be able to see which one is stuck all the way open. worked for me way back then.

 

Check rear brake adjustment.

Make sure you don't have any leaks. The line to the rear loves to start leaking slowly, and it doesn't always make it to the ground when sitting still. (till it blows completely)