1990 C1500 ABS (RWAL) removal.

Whipped96 said:

My truck is a 96 so I’ll need to add a proportioning valve. I got one off eBay but it looks to be the wrong way on the bracket, can anyone confirm?

Click to expand...

Whipped96 said:

You must be registered for see images attach

Click to expand...

Pale ***** said:

@Whipped96 Were you able to get that one to work? Im looking at a similar one on Amazon

Click to expand...

hefftone said:

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.

Click to expand...

DRAGGIN95 said:

I copied this from another post that I made. I have done this several times, on 88-94 2wd truck like mentioned you remove the ABS control module and rear abs valve, be sure to keep the proportioning valve though you need it to keep proper brake bias from the front and rear brakes. Anyway run a new piece of line from the rear brake line junction on the frame just below the firewall to the proportioning valve and that's it. For 95+ originally there are 2 independant lines running to each front brake caliper that run directly to the ABS unit, there are 2 way's to deal with this, either unhook the both front lines at the abs unit and install a tee, or what I do is go the salvage yard and buy the front brake lines and proportioning valve off of a 88-94 the front lines on a 88-94 tee together originally so with this method there are no other tee's needed, I can get it all locally for $10. The rear on the 95+ still only uses 1 brake line that runs directly to the abs unit, it can be unhooked and hand rebent to hook up to the 88-94 proportioning valve, or you can just buy a new piece and run it from the junction on the frame under the firewall to the prop. valve. It's not difficult to do at all. Also one interesting note when the power and other plug's are unhooked from the abs unit on the 95+ the abs in dash light does not come on, even though you would think it should.

Click to expand...