The truck has been surging to a stop, and we are shotgun replacing things now..

1996 2wd 1500 automatic 5.9L

230k miles

ABS light and BRAKE light are now on after changing rear axle bearings and seals, and had the drums turned with new shoes. The lights stay on at idle , but when you push the brake pedal down , the lights go away.. let it up, and both lights come back on.

we were looking for anything while we had the rear end torn apart and found no problems. The truck still surges when stopping....

 

replaced the bad ABS sensor in the rear axle housing.

Lights as still on.

When I unplug the single wire connector located on the drivers side of the brake master cylinder , the lights go away on the dash... plug it in and they come back. looks like an abs distribution block.

 

4wal, or Rwal?

Check the brake line going to the rear brakes. See if it isn't seeping fluid somewhere. How does your pedal feel? Does is go down slowly if you have your foot on it? Do your brakes seem to need more pedal effort to stop?

 

RWAL - replaced the abs sensor already on the diff.

brake pedal is fine, no leaking lines or fittings..

When I pull the ABS fuse out and step on the brake pedal the lights illuminated on the dash remain on.. however, when I put the fuse back in, and step on the pedal the lights on the dash go away, until I release the pedal - then they come back on again.

the truck still lurches forward as we stop.. brake system has basically been completely rebuilt and we haven't solved that issue yet. Hoping its not the transmission (automatic)

This is a Florida truck and has never been put in the water at the ramps, and never been offroad. never towed anything over a 14' LUND with it.

 

Ok, just as an experiment...... pump up the brakes, and hold the pedal, then crack open one of the front bleeders. Close it back off, see if the lights stay off when you release the pedal. If they don't, try the same trick, but, open one of the rear bleeders.

 

On the ABS distribution block ? each wheel ?

I'm trying to understand if The ABS distribution valve isn't stuck one way.

 

I think that that little block also contains the proportioning valve, and if it is slightly off centered, the behavior you are seeing would be consistent with such a condition. The idea of putting some pressure on it, and then cracking open a bleeder, is to 'shock' it back into the correct position. Under normal circumstances, I would expect it to automatically center itself, but, I have yet to figger out what "normal circumstances" are......

 

could I theoretically crack it at the proportioning valve then ? where the abs plug is at. Being it's under pressure it shouldn't introduce air into the system as long as I close it while its still releasing pressure..

 

Update - I removed the little rubber covers on what was decided to be the ABS Proportioning valve.. there was one on the front and one on the back.

the front one has a little brass plug sticking out of the center of the port, and the back didn't. Morbid curiosity , I pushed the brass plug back in, and started the truck up.... ABS and BRAKE lights are now off ! I pushed the pedal a few times and they never came back on... I checked the brass plug really quick , and it had been pushed out again! ... everything works as it is supposed to though now. so i just put the rubber covers back on and drove the truck around a bit, everything seems great...

except my normal surging while coming to a stop, in forward and reverse is still present.

Appreciate the help! Now on to continue searching for this solution lol.

 

Neat trick. So long as it worked, that's all ya really want anyway.

does engine rpm bounce around when coming to a stop?