1990 C1500 ABS (RWAL) removal.

[gimmel1]

I winder if this could be made to work like a line lock of sorts. Anybody know?

 

[gimmel1]

no one??

 

[BackInBlack]

I haven't done this but it seems promising. I'm one to use my phone or tablet while I'm working, so I took all the pictures and all the steps and made a pdf file. If anyone would like it let me know.

 

[flh69]

This is easy to do, but with a little information it will make it easier and more straight forward. My truck is a 1990....it seems that this should be the same on c1500's from 1988* to 1994*.
What you need.
1/2" wrench/socket
9/16" and 1/2" flare wrench for brake lines.
5/16" male x 1/4" female brake line adapter fitting. ie, EDELMANN #258450 (available at O'reilly auto parts.....about $5.)
15 minutes + time to bleed your rear brakes.


The Master cylinder has the fluid reservoir on top. The isolation dump valve is below it (to be removed). To the right of that is the proportioning valve (gotta keep that). Attached to the proportioning valve is the control box (black plastic with wired connectors).

You must be registered for see images attach

Lets Start off by removing the control box. First, remove the connectors from the rear. The top one is part of the vehicle harness. The lower plug connects to the other part that will be removed. Then, jiggle the box and pull towards the front of vehicle. Should slip off.

You must be registered for see images attach

now we should be looking like this....

You must be registered for see images attach

Next, disconnect the two lines from the bottom of the isolation/dump valve...one of the lines is very short and connects to the proportioning valve. Disconnect from the proportioning valve as well. After those are removed, simply remove the two bolts (1/2" socket/wrench) from the the top of the valve where it attaches to the bracket.

You must be registered for see images attach

With all that crap out of the way, its easy to see what we have left to do, which is not much.

You must be registered for see images attach

You must be registered for see images attach

I bought this fitting at Oreilly auto parts for $5.49 plus tax. It will allow you to use the existing brake line and screw into the proportioning valve. It is EDELMANN 258450. The male threads are 5/16" and the female are 1/4". This is a brake fitting. You can probably find something similar but those are the right dimensions.

You must be registered for see images attach

Screw that in the bottom of the proportioning valve. I used some teflon tape for good measure. The use a little bending to reposition the line and tighten it up.

You must be registered for see images attach

And that's it! Bleed your Rear brakes, hopefully you have will better pedal feel. Mine have improved greatly, but still feels a little spongey for my liking.

I'm a nubie here but have been lurking for a while. I have a 1990 K2500 with 225,000 miles on it that I just had the rear drums, brake shoes, & and axle seals replaced because of leakage and the right rear wheel would lock up during braking. After the replacement of these parts the truck developed a terrible rumbling from the rear end when braking from a high speed & the right rear wheel still locks up. Could the RWAL be the problem? If so, what do you do with the two connectors that you disconnect?
NOTE: I unhooked the bottom connector some time ago because the brake warning light came on & I needed to get it thru inspection. The wheel was locking up before I unhooked the connector.

 

[77Impala]

Did the RWAL delete today and glad I did so. Very firm brake pedal, better than since I have owned this truck!

 

[77Impala]

I'm a nubie here but have been lurking for a while. I have a 1990 K2500 with 225,000 miles on it that I just had the rear drums, brake shoes, & and axle seals replaced because of leakage and the right rear wheel would lock up during braking. After the replacement of these parts the truck developed a terrible rumbling from the rear end when braking from a high speed & the right rear wheel still locks up. Could the RWAL be the problem? If so, what do you do with the two connectors that you disconnect?
NOTE: I unhooked the bottom connector some time ago because the brake warning light came on & I needed to get it thru inspection. The wheel was locking up before I unhooked the connector.

Check or change the RR drum on your truck. Also recheck that the brake shoes are properly adjusted.

One of the connectors (4 pin) is removed when you delete the isolation/dump valve. The other connector you can cut the wires at staggered lengths and tuck back into the wire loom. That is what I did with mine. Be aware that the orange wire will be hot so if it shorts out you will need to replace the 15 amp brake lamp fuse.

 

[92BlkK1500]

I did this today as money allowed I didn't need the fitting though the brake line screwed straight into the proportioning valve.

 

[Sampuppy1]

I really need to consider doing this to my 97. My brakes can't decide if they want to be spongy or solid. I like having solid brake pedal response. But more often than not I have half pedal travel before it grabs and slows down. I'll be writing this one down on the to do list.

sent from a likely flagged smartphone.

 

[ScoobyJD]

Do I have to keep the orange wire that is coming off of the proportioning valve or can I just cut it off? Also what the heck is it for?

You must be registered for see images attach

 

[someotherguy]

That's for the brake warning light on your dash.

Richard