1991 Scottsdale Brakes Issue

[CADET115]

Ok so I already tried to get some answers in the pinned thread above talking about 1990 RWAL removal but so far no one has answered. I have a 1991 Scottsdale 5.7L V8 Manual. My father and I have slowly gotten the thing road worthy but the last thing is the brakes. I read the thread and some talked about just completely removing the ABS system for the rear brakes since it wasn't a very good design to begin with. My question is regardless of removing or not shouldn't I be getting some brake fluid going to the rear line to begin with or is the isolation dump valve causing the issue. I understand the proportioning valve problem and have the bleeder tool to deal with it. The thing is even after putting in the bleeder tool we aren't getting any fluid to the rear brakes. Do I need to have the truck running to get the thing to work or just have the key forward. Any help is greatly appreciated.

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This is just a picture before I had the bleed tool. Curious on why it's not working, could it be possible I don't have the pin forward.

 

[evilunclegrimace]

First thing is to reinstall the wire for the warning switch and see if the warning light is on for the brake system. If it is then remove the rubber cap on the front end of the combo valve and see if the valve is stuck off center. If it is, the end of the valve will be sticking out past the end of the combo valve and that will prevent fluid from reaching the rear brake cylinders . Push it back on center and hold it in while the brakes are bled to equalize the system. There is a tool for holding the pin from pushing off center but they are a bit hard to find.

 

[CADET115]

First thing is to reinstall the wire for the warning switch and see if the warning light is on for the brake system. If it is then remove the rubber cap on the front end of the combo valve and see if the valve is stuck off center. If it is, the end of the valve will be sticking out past the end of the combo valve and that will prevent fluid from reaching the rear brake cylinders . Push it back on center and hold it in while the brakes are bled to equalize the system. There is a tool for holding the pin from pushing off center but they are a bit hard to find.

I have the tool for bleeding the system. I'm just not sure if I have the metering pin centered or not. I could've sworn we got it back to center but maybe we didn't. I'll look into it today.

Edit: Is there anyway to know that the valve has been re-centered without the brake light because I'm pretty sure my E brake is also causing the light to be thrown since the E brake doesn't work.

 

[arrg]

Went through this with mine. Tried everything under the sun and could never get more than a trickle from the rear bleeders. Then I changed the rear brake hose and it all worked like it's supposed to. If you haven't changed all 3 of the 30 year old rubber brake hoses on your truck, I'd highly recommend that. You can get all 3 for less than $30.

 

[CADET115]

Went through this with mine. Tried everything under the sun and could never get more than a trickle from the rear bleeders. Then I changed the rear brake hose and it all worked like it's supposed to. If you haven't changed all 3 of the 30 year old rubber brake hoses on your truck, I'd highly recommend that. You can get all 3 for less than $30.

ATLAST WE HAVE FOUND PROGRESS
Did lots of experimenting and found the master cylinder wasn't even getting fluid out. I replaced it and now I actually have front brakes to start. My next issue is the fact that the proportioning valve is blocking fluid from getting to the rear so now I'm just gonna order a new one, unless I can find a way to recenter that annoying thing inside. Until then I'll just be driving it with front brakes.