1990 C1500 ABS (RWAL) removal.

[bacon612]

Pull the bulb....I yanked most of my warning lights.

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Tyler/T-Unit

So there is no way to reconnect the warning system? I get pulling the bulb but its reasonable to be notified of a loss in brake pressure, isn't it?

 

[Sampuppy1]

So there is no way to reconnect the warning system? I get pulling the bulb but its reasonable to be notified of a loss in brake pressure, isn't it?

If I need a light to tell me my brakes aren't working after driving the same vehicle daily for almost 8 years...... I shouldn't be calling myself an enthusiast.

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Tyler/T-Unit

 

[Macfluke]

I have a 1989 C1500 Silverado that has had a soft pedal for 20 years... I dumped the dump valve and the braking improved tremendously, I also replaced my original master cylinder 1" bore with a new master cylinder 1 1/8" bore and now it stops on a dime with a firm pedal... I did have to use the Edelmann 258450 adapter...

 

[Lance smeal]

Ok so I did this mod today..90 k1500
No adapter needed. All new rubber lines front n rear.. Front brakes bled perfect, prop valve bled out,
NO FLUID AT REAR BRAKE LINES !!
how do I reset prop valve ? Is there a little push button from and rear on the prop valve ?
Thx

 

[77Impala]

...how do I reset prop valve ? Is there a little push button from and rear on the prop valve ?
Thx

There is no button on the proportioning valve to manually reset. It should try to reset every time you push the brake pedal. Right now it thinks you have a leak in the rear side of your brake system. Make sure all your rear lines are tight.

You may even need a vacuum pump to bleed the rear brakes.

 

[Lance smeal]

All lines are tight... Ill get a new mity-vac tomorrow (handle broke today before doing brakes of course) .. Try again ..

 

[Lance smeal]

It did whatever it was supposed to n I was able to bleed left rear w mitt-vac...moved to right rear n nothing... So had wife jump in , open bleeder, wife pushed brake, pushed all kinds of nasty fluid, did that
5-8x n refilled master, did it a bunch more.. Always good solid fluid coming out.. Fronts bled out perfect the day I did the brake lines.. Driving truck its not really any better than before (other than safer w all new brake lines) pedal is still "meh" .. No astonishing results like others have gotten.. Gonna drive it a bit n see if maybe some air will migrate on its own out of the system ..

 

[RLK1]

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).

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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.

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now we should be looking like this....

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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.

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

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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.

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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.

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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.

 

[Moparmat2000]

If i do this on my 94 C1500 will the brake warning light then stay on all the time? I want to have the warning lamp come on if theres an issue, but not stay on if i remove the box.

 

[Crookedaxle]

Add me to the list. 1993 GMC K2500. No adapter needed. It took me under 10 minutes to do.