I have a 2001 3500 that just started giving me brake problems. Hopefully someone has experienced the same problem and can give me some help. The brake pedal is full sometimes but sometimes it goes nearly to the floor. It happens somewhat randomly so thats why I can't figure out whats causing it. When it goes to the floor I still have brakes but it is obviously harder to stop. The brake light and abs light are on. It has disc brakes on the front and rear. Any ideas? Thanks in advance for the help!

 

Sounds like master cyl to me, but could be ABSpump/assy.

try with engine off, and stand on brake pedal, if pedal slowly sinks to floor, I'd suspect bad MC (internal leakage past seals)
think a new MC is around 60$

 

sounds like it needs a new master cylinder

 

You've probably got the Hydra-Boost system in your truck. Could be air in the system. Check all your brake lines for a possible leak.

You also might try draining and replacing the power steering fluid.The two systems run off the PS pump. Just a few thoughts.

Kurt

 

Draining the power steering fluid and putting new fluid in the system has fixed the problem for now. Just thought I would share that with anyone else who might experience this problem.

 

sounds like a bad ABS sensor to me and the ABS is defaulting off, which would feel funny, or cycle on and off. Check the continuity on the ABS lines (all three of them) to the front left engine compartment computer....