How to reset brake combination valve?

[njsteve]

Ran into a dilemma yesterday. I was installing the new repro bleeder master cylinder and couldn't get the combination valve to reset in order to get fluid to the back brake circuit. Driving the car onto the trailer with the rear brake line unhooked (though plugged) set off the BRAKE indicator light.

I tried everything: cracking a front bleeder and keeping the rears shut, then stepping on the brakes only resulted in the dash light turning out, indicating that the valve reset, but it must be internally blocked since the reset pin was still sticking out and no fluid was moving the the rear. I then put a plug into the rear circuit port of the valve to provide something for the fluid to press against and build internal pressure - once again the ligh would reset but no valve movement. Finally I just said the heck with it and removed the valve and put in a spare that I luckily had sitting on the shelf.

Anyone have any idea how to reset the valve? I tried removing the indicator plug with the electrical lead from the top, and manually moving the slider valve in the tiny port it engages with, but no luck there either - the slider wouldn't move. Pushing on the metal indicator stem doesn't budge it either.

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[parkbrau]

I'm assuming that the park brake pedal is not pushed in just a little bit? I had to check. Two different switches make that light go on, the one on the park brake and the one the distro block. Disconnect the park brake, if it goes out you may have a ground problem there, and do it on the block as well, but with the e-brake wire attached. Thats trouble shooting the electrical side.

If no electrical gremlin is present then just stomping on it "Should" center the spool in the distro block and turn it off. Assuming the system is bled and equal pressure is present at that valve. If the pressure is not equal it will cause that spool to move and ground out and make the light come on.

Give your brake system a total flush.

[mockingbird812]

Sounds like you have been there before. Good advice!

[Lynn]

Also, if you haven't tried yet, I can remember having to push in that pin to reset. Used a large set of groove joint pliers. Foot off the brake. Depress pin. Bleed rear first; once you have no air, move to the front, first right, then left.

[njsteve]

Emergency brakes were disconnected and not activating the light. The Catch-22 problem was that there was no way to feed fluid into the brake line feeding the rear of the car, so long as the valve was in its activated position. Thereby preventing the ability to reset the valve by stepping on the brake pedal. One circuit would be full of air, which would keep the valve activated. That was why I then tried putting a plug into the rear circuit outlet, which didnt work either. So I just replaced the entire valve and then flushed and bled the entire system successfully.

The pin is not moving at all which leads me to believe that it is stuck in the bore due to internal crud buildup which I imagine is pretty commen occurrence.

Logically, I would think if I now reinstalled the old valve, now that the system is full and bled, that maybe the now filled rear curcuit would provide the resistance needed to shift the valve back to its normal position.

[Lynn]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: njsteve</div><div class="ubbcode-body">
The pin is not moving at all which leads me to believe that it is stuck in the bore due to internal crud buildup which I imagine is pretty commen occurrence.
</div></div>

You are correct. I would not use it if the pin is stuck.

[njsteve]

I placed the valve in the hydraulic press and gently pushed the extended pin back in. It moved with a slight pop and it's now back in the original centered position. I'll keep it as a spare for the future.