my proportioning valve is out of center due to improper bleeding after replacing the rear calipers (self inflicted) and is now stopping the flow to the rear calipers. does anyone know how to reset it so I can bleed the brakes?

I had that same problem once, and I ended up taking the valve apart. In my situation, that was a good thing as I found a chunk of rubber (from previous owner) which had somehow found it's way into the valve. There's probably a simpler way of re-setting the valve, but at least you know it is possible by taking it apart.

Just a FYI... it should actually be referred to as a combination valve.

[This message has been edited by Patrick (edited 07-02-2014).]

Thanks Patrick , I hope there is an easier way .

The valve slides to one side or the other when there is unequal pressure on either side of the piston inside the valve body. That only ever happens when you have a hydraulic leak somewhere, but once it trips, it stays that way until you do the following. Once you repair the leak, reset the proportioning valve by starting the engine (to get maximum boost) and press the brake pedal as hard as you can for a few seconds. That should equalize the pressure on either side of the piston inside the valve body and cause it to slide back into it's neutral position.

If that doesn't work, then you've either got air in the brake system or you still have a leak somewhere. You can test for a leak by pressing and holding the brake pedal hard for about 30 seconds. If you feel the pedal slowly sinking to the floor, then you have a leak and there should be enough fluid that's been forced out for you to find the problem area easily.

quote Originally posted by Patrick: I had that same problem once, and I ended up taking the valve apart. In my situation, that was a good thing as I found a chunk of rubber (from previous owner) which had somehow found it's way into the valve. There's probably a simpler way of re-setting the valve, but at least you know it is possible by taking it apart. Just a FYI... it should actually be referred to as a combination valve.

See my Cave, Combination Valve

If CV valve is good then will "reset" by its self when normal pressure on both sides are good. Normal foot pressure should do that when brake is push 1 to 3 times. Push hard might work too.

If CV won't reset then likely need a new CV.
Taking apart a CV can be trouble. CV can use label "No serviceable parts inside."
Many times reset fails cause by corrosion from "wet" fluid or water thru switch port.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

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Thanks for the help and info guys! It is now back to center, and the brake light is off.

Nice colour diagram in this thread, but no mention of the reset. Good to know...
https://www.fiero.nl/forum/Forum2/HTML/109173.html

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86 GT built 2.2 ecotec turbo
rear SLA suspension
QA1 coilovers on tube arms