I have a '99 1500 4x4. The abs and brake lights both came on. the brakes sink but build up after 2-3 pumps. The fluid is good at the recommended level, I checked under truck and behind each wheel and there no leaks or in the lines. The fluid has not been low. less than 1 year ago, I changed the rear ABS sensor on the rear end cuz the speedometer wasn't registering until it hit 30 mph so it shouldn't be that. I read to brake while in reverse to reset the back brakes; that did not work and to press the brakes while the engine is off as that may indicate the master cylinder going out; the brakes started going down but built up normal pressure after 2-3 pumps. Just like when the truck is running. Any input is appreciated as I respect the collective knowledge on this site. I've researched this issue on the WEB and have not found the exact set of circumstances I have experienced so I hope this isn't a redundant question. Thanks for listening to me.

 

My dads 98 ram 2wd 5.9 has same problem

 

Yea, It's pretty frustrating because it doesn't seem to follow common brake problem symptoms. Maybe someone will help both of us...LOL.

 

He gunna try to replace rear speed control sensor see if tgat helps

 

If you have to pump up your brakes, you have a problem. Likely the line going to the rear is leaking. Generally right back by the gas tank, where it's hard to see. Fluid won't necessarily hit the ground right away either.

 

Bully frog,I replaced that sensor last year. The speedometer was not registering until around 20mph or so. After I replaced it, it worked fine after... I don't think that is my problem.... good luck...Hey You, thanks for that. I'm going to look closer at the lines around the gas tank like you said... My problem happened suddenly, no warning signs.

 

That sounds a LOT like a popped line.

 

Just noticed his e brake line is snapped

 

OOo, yeah, if that was a recent occurrence, that would make the rears go out of adjustment RIGHT quick. (and give the strange pedal behavior as well.)

 

Just to follow up.. months later..LOL... you guys were right..It was a leaky rear brake line... it was wrapped up in so much tape that I really didn't notice it right away and didn't look at it until it had been sitting for weeks and any wet spots dried up pretty much... anyway.. I bought new lines for $35 dollars each and changed the other side while I was under there... all good now... thanks again. I appreciate it.