Try to bleed the rear brakes. If you do not get sufficient fluid out, the lines are bad.

And I have vehciles that are as old as I am (and I have 10 grandkids to give you an idea) and vehicles with over 250,000 miles, and I don't and haven't changed brake fluid. Only drain some as cylinders are changed, etc. If fuild is clean, it is good. If it isn't you may need to change, but do it by bleeding. And then find out why it is getting dirty, like poor seal on master cylinder.....

 

I'm sorry, I'm not trying to shut down every suggestion you have because I know you're very knowledgeable and I look forward to reading your posts, but the reason I found out that the rears weren't getting any fluid was when we tried to bleed the brakes, and found that the fluid doesn't seem to be getting past the prop valve (unless I'm misunderstanding the direction of the flow through the prop valve. Fluid comes out of the top opening closest to the fender on the driver's side of the top valve. Fluid does NOT come out of the lower opening closest to the fender on the driver's side of the prop valve.

 

Follow the lines for which way flow is going. Should be easy to find the rear brake line, and crack it loose at the p-valve, and see if anything comes out. Step gently on the pedal, or all it will do is offset the safety valve in the p-valve.

If you don't get any fluid out there, crack open the FEED line for the rear circuit, (which I think is actually the FRONT line on the M/C. See if you get fluid flow there.

Just crack the lines loose a bit, and have someone step down on the pedal, and HOLD it there. Re-tighten the line before they let the pedal up, to keep from sucking air into the system.

 

Is the master cylinder good? Wheel cylinders and master cylinders have a lower MTBF than proportioning valve. You can crack the lines on it as mentioned by HeyYou, but I would do it at MC as it may be easier to get to. If MC is not right, PV will not get enough fluid. But it should throw a code if PV is bad. Should.....but then again.....not everything works as it should I suppose.

 

I pulled the rear proportioning valve off both my dodges and threw them in the trash. They are worthless and just cost more money in the end to replace when they blow. I just replaced them with a flex line and haven't had any problems.

 

That really screws up your brake bias.......

 

Speaking of brake bias... I swapped out the master and that seems to have been the problem. Bled the system and got fluid to come out of all 4 brakes. The problem now is that the rear brakes lock up with mild braking. What the hell could be the issue now. Also, does anyone know the purpose of the buttons on top and bottom of the prop valve?

 

How's the pedal feel? Maybe still some air in the fronts?

 

I don't feel a difference when braking, I have been running them this way for years and tow everyday with them without any issues. Reguardless The proportioning valve only limits fluid to the rear under hard braking, under normal braking it does nothing giving a 50/50 split, So changing that will only effect hard braking performance

ALSO read here....
http://dodgeram.info/tsb/1998/05-04-98.htm

 

Hey, well I too am having issues and before spending $200 on a new proportion valve maybe yall could shed some light on my situation.
When I press the brakes the rear engages hard with a jerk almost causing me to skid, and the front will pull to the left. I thought that maybe the front left caliper was bad and changed it out and it still hung up. after noticing that the rubber seal had a tear I exchanged it for another caliper and still the same result. I also went ahead and changed the front brake hoses being that they looked old anyway. The problem still was there. Taking some advice I changed the master cylinder, and what do you know the issue still remains. Err! well all thats left is the proportion valve, but is there any other advice I should look in to before I end up with a complete new brake system as I'm almost there? And obviously I have flushed the brake system.