Brake bleeding w/ rear ABS

[photo-tom]

Hey All,

Tried pressure bleeding the system the other day. Started in the rear and neither side had any flow. Turns out I threw the prop valve right away, which triggered by ABS light. Now I have no rear brakes and need to reset the valve somehow.

I've seen people delete the ABS, use a scan tool, gravity bleed, pressure bleed, etc. No clear method on how to bleed these trucks.

Does anyone have wise words as to properly:

1. Reset the prop valve
2. Bleed the system with rear ABS

Truck is a 94 c1500.

 

[east302]

You can rule out the scan tool, that would only apply to the later models. I had that issue on my 98, which has a different ABS than your truck and uses a combination valve (not sure if yours is two separate valves or not) but here’s how I got mine to reset.

The combination valve on mine has a rubber cap on the end. Pull that off and there’s a pin underneath. When you press the brake pedal, the pin extends. On mine, I held a flat screwdriver flush with the pin to keep it from extending and had someone pump the brakes. Don’t press the pin in, just keep it from extending.

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Your proportioning valve may have something similar on it. It may be worth a shot.


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[blacksport]

i use a hand vacuum pump works like a champ.
https://www.amazon.com/dp/B073LMMJ4...t=&hvlocphy=9009939&hvtargid=pla-351300927115

 

[east302]

i use a hand vacuum pump works like a champ.
https://www.amazon.com/dp/B073LMMJ4...t=&hvlocphy=9009939&hvtargid=pla-351300927115

With that kit, do you connect the rubber elbow fittings to the bleeder or just use a piece of hose? I had a MityVac kit with those and never could get it to seal.

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[photo-tom]

You would attach the fitting ends to the hose, than apply the end to the bleeder valve.

 

[east302]

Thanks, that’s what I figured. I guess the ones in my kit were just cheap.


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[blacksport]

i use the elbow sometimes the hose will work without the elbow you never get a perfect seal as long as it's pulling fluid you are good it will still pull a little air from around the bleeder threads.but the back is still a PITA i replaced all my rubber lines,the rear was locking up because the line collapsed,it took a minute but i got it to bleed out with a MityVac.

 

[photo-tom]

You can rule out the scan tool, that would only apply to the later models. I had that issue on my 98, which has a different ABS than your truck and uses a combination valve (not sure if yours is two separate valves or not) but here’s how I got mine to reset.

The combination valve on mine has a rubber cap on the end. Pull that off and there’s a pin underneath. When you press the brake pedal, the pin extends. On mine, I held a flat screwdriver flush with the pin to keep it from extending and had someone pump the brakes. Don’t press the pin in, just keep it from extending.

You must be registered for see images attach

Your proportioning valve may have something similar on it. It may be worth a shot.


Sent from my iPhone using Tapatalk

Tried this with the proportion valve yesterday. Didn't work—still no rear brakes.

I installed new front calipers because the old bleeder valves were seized, and for $22/caliper, why the hell not. Spent the better part of an hour trying to bleed the front as well. Still need to resolve, but will have answers when I come back from working on my squarebody out of state next week.