Hey guys I'm starting to hate this damn truck! (2006 4.7 4x4)

Picked up the truck for cheap, had brake issues. Swapped the front calipers/rotors/pads, and the rear drums/shoes/cylinders/adjuster.

Still has the same brake issue, pedal goes all the way to the floor and then you have to press a bit for it to actually stop.

Swapped out the master cylinder (new) and the brake booster (found a cheap one at the junkyard) because I couldn't get the master cylinder off of the old booster.

Bled everything, bled the master cylinder and STILL have the brake issue. Even better now, somehow the new brake booster must have a shorter shaft as the brake pedal no longer travels back far enough to engage the brake light switch.

Anyone have any ideas?

 

Forgot to add, the ABS and Brake lights are both on.

 

The abs and park brake light being on is because the sensor that comes with the new master cylinder does not work as intended. It has the wrong resistance and reads low brake fluid even when full. Replace the sensor with a Mopar one, or the old one, and it will fix that issue. As for the soft pedal, did you properly adjust the rear brake shoes after installing? Or it could be a damaged/worn rubber brake line. And when changing the brake booster or the pedal, you are supposed to replace the brake switch as it is set up one time for the current position of the brake pedal. And new one is needed to be set for the brake lights.

 

Oh wow, thanks for the info on the brake pedal sensor. Had no idea they were made that way.

I was afraid it would be that sensor, should be easy enough to put the stock one back on!

I believe I did adjust the rears correctly? When trying to spin the wheel it just barely is rubbing against the shoes. Had to brake loose the parking brake levers too as those were rusted tight. They were kind of a bitch to tighten. Still not 100% sure I got the new adjustment mechanisms on the correct sides.

I did order an abs capable obd2 tool in hopes that somehow the abs won't let it bleed correctly.

 

I'll second checking the hoses. I once changed calipers and master cylinder on a car trying to solve a soft pedal when a friend helping me bleed it noticed a hose swelling when the pedal was pressed.

 

Just an update, the scan tool confirmed its just a faulty sensor.

Did the abs bleed procedure, did manage to get some air out of one of the drum sides.

So heres the rundown. The brakes do work but only after you pump the pedal once or twice. It's as if the power assist is too "strong" if that makes sense. What else could it possibly be?

 

When you press and hold the brake down, does it feel like the pedal is slowly falling away under your foot? Usually it's an issue with the master cylinder, or air in the system. The master cylinder is supposed to be bled before the brake lines are attached, not sure if that makes any difference, but i imagine they recommend that way for a reason. Any issue with the brake booster will cause the pedal to feel too firm and hard to press.