So, I took my truck to a local shop to have the front brakes checked out since they were getting hot, smoking and sticking. While I was having the brakes checked out, I asked them to go ahead and flush the system. While they were checking they system to see what was causing the issue, they found that the rear brakes weren't getting any fluid. They traced it back to the proportioning valve saying that the valve was allowing fluid to go to the front brakes, but not to the rear. But they also said that since the ABS is in the rear, replacing the valve would be a job for the dealer since the ABS module would have to be messed with in some shape or form (I don't remember the exact details). Does it seem right that the ABS module would have to be messed with when replacing the valve? I'm asking because it seems like replacing the valve would be a fairly straight forward job, but the stealer wants to charge $108/hr. which seems absolutely ridiculous to me - we're talking about a 2001 Dodge, not a Mercedes here...

 

RWAL or 4WAL?

Is your brake lite in the dash on?

 

Its possible that it would have to be messed with...
For instance If you are bleeding your brakes you may need a scanner to activate the servo motor in you ABS unit to clear all the air from the system. I only have rear wheel abs in my 96 but disconnected it anyway due to the motor leaking.
As for the proportioning valve...
Its used to shut off fluid to the rear to prevent skidding out and causing you to lose control. If your rear brakes aren't getting fluid then only your fronts are stopping which would cause excessive glazing and front brake failure. You may want to sand your pads and maybe get your rotors cut.

 

RWAL and no brake light in the dash. Although a few months ago, when I replaced front pads the brake light came on for a minute until I shut off and restarted the truck. Hasn't come back on since.

 

If the light isn't on...... I would start looking for other causes.....

 

So a bad prop valve would cause the light to come on? Would the master be the next logical source if there's no fluid coming out of the prop valve?

 

The proportioning valve serves a couple purposes.

First and foremost, it balances pressure between front and rear, (usually like 70/30) so the front brakes get full pressure, and the rears do not.

Second, its a safety valve.... if one circuit fails (front or rear), the valve inside it will be pushed off center, and turn on the brake light, and block pressure (or lack thereof) going to the failed circuit. Aside from an ABS failure, that is the ONLY reason the brake lite will come on. (ok, also if the e-brake isn't fully released....)

If the brake lite is NOT on, and you aren't getting pressure at the rear wheel cylinders, suspect the soft line going from body to axle FIRST.

 

I checked all the soft lines and didn't find any leaks or kinks. However, I did have a new development today. Took the truck for a drive around the neighborhood and the brake pedal was behaving as normal. Then, suddenly, the pedal became mushy and went down to the floor while still stopping the truck. I messed with it some more and found that when I step on it hard, it has some resistance, but when I ease into it, it just sinks down. I did a little bit of research and read that this can be cause by a bad master cylinder seal. Then I read that the seals can fail if the brake fluid hasn't been changed in a while and then you attempt to bleed the brakes. Something having to do with buildup at the end of the cylinder that doesn't get used under normal circumstances, but can cause damage when the pedal is dropped to the floor during bleeding, which would make sense since I don't know when was the last time that the system was drained before I had it done a couple of days ago. This is all fine and good, but could this also be the cause of the lack of rear brakes? I'm thinking no since the the rear brakes seem to have failed BEFORE the fluid drain, but input is greatly appreciated.

 

Either that, or the rear brake line blew out.

Did the brake lite come on? Does it come one when you first start the truck?

 

I would agree with you, but there are no leaks and the reservoir is full. I assume you're asking if the brake light is malfunctioning - it comes on with the rest of the warning lights when I turn in the ignition and also when I use the parking brake.