Dump valve = HCU. You could have a short in the harness, and I'd check for that before dropping the money on a dump valve. Unplug the dump valve and the RWAL box and check cavity 11 on the RWAL plug for a short to ground.

PartsAmerica has the dump valve on their site for $149 with free shipping. Core gets dropped at your local store (Advance, Checker, Schuck's, Kragen, and Murray's are all affiliated with PartsAmerica).

 

Thanks, could it also be the speed sensor in the pumpkin?

 

will a dump valve off of a 1992 dodge dakota work if my valve is shot or is that a different setup?

 

I also have a rwal problem. The electrical connection at the rear axle corroded off. The wire is hanging loose and it looks like both the connector on the axle and the one on the wire are beyond repair.
From what I've read on this forum, the rwal system on these trucks wasn't worth much anyway, so it's probably not worth replacing parts. I could make the warning lights on the dash go away by removing the bulbs, but the other functions of the brake warning light are probably worth retaining.
Does anybody know what wires to cut or short to make the "anti-lock" light go out and the "brake " light function normally for all its other warning functions?

 

Will plug in and work - sort of. The accumulator is too small for the bigger wheel cylinders on our trucks, so it will not provide enough capacity for a long panic stop.

 

ok, thanks, what about the speed sensor?

 

Yes, that will work fine.

 

thanks, i found it at my local auto salvage yard for $5

 

Is the dump valve the device that is bolted to the inside of the frame? There is one on the drivers side by the rear tire and one on the driver side front tire. what does this do? Is this the part that actually prevents the wheels from locking up in a panic stop? The truck I have has the front one hooked up but the rear one was cut with the sensor still hooked to it.

My ABS light has been solid so I assume it's something to do with the bypass that they attempted to do. My plan is to convert to disc brakes in the rear end as it's easier to maintain but that won't be for awhile. I need to fix my leaking caliper first then assess what I have going on in the ABS department.

 

The one in the back is the dump valve, the one in front is the proportioning/combination valve...Mark

 

Do these do anything? Curious what their function is. If I get disc brakes should I utilize these or come off the master cylinder directly?

 

The RWAL setup is not large enough to deal with disc brakes, you'd want to bypass it.

 

Okay, thank you!

 

I've never looked close, but would it be possible to drill and tap a hole to screw a hose into, and hook in another tank to enlarge the accumulator?

 

The accumulator is a spring and piston setup much like an accumulator in an automatic trans. Simply adding a tank wouldn't do anything to help.

During ABS braking, the dump valve releases tiny amounts of fluid into the accumulator 10 times per second. With calipers the amount of fluid released wouldn't be enough to unlock the wheels.