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We recently had problems with our power brakes. As a result, we replaced the brake lines, the proportioning valve and the master cylinder. Everything seems OK now except we can't get the Brake Warning Light to go off on the dash. Does anyone know what the problem is? We bled the brakes and the Master cylinder and think there is no air in the lines.
First make sure light is not on due the parking brake. The other reason is the pressure differential has moved inside the metering block causing a ground lighting your warning light. Finally you have a wire that is shorted to grounded for ether system.
First make sure light is not on due the parking brake. The other reason is the pressure differential has moved inside the metering block causing a ground lighting your warning light. Finally you have a wire that is shorted to grounded for ether system.
likely the pressure differential in the block...I know there are threads on here about resetting it. I triggered mine one time during brake bleeding and had to reset it (it was years ago, so I don't recall the procedure, but I found on here somewhere).
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Yes! Slamming your brake pedal can reset the valve but first disconnect the brown wire (on the valve) and if the light stays on then adjust the switch on the parking brake.
Depending which way the valve moved:
Another way to reset the valve is to have a helper hold pressure on the brake pedal and open and close a front bleeder, if that doesn't work bleed a rear wheel
My light is on as well. I figure it has to be something besides the proportioning valve since the valve is new and I have no issues bleeding the brakes. I am pretty sure if the valve has shifted, it would prevent bleeding. I am hoping it is a ground or the parking brake switch.
Now that I can work on the car, I pulled the wire on the proportioning valve, and that turned off the light. So I guess it is the switch at the proportioning valve. The valve and switch are new and I am able to bleed the brakes. It must be slightly shifted, enough to trigger the switch, but not to block the line completely.
Depends on the year car you have.
1968 - 1973 the block is a brake failure warning light, it doesn't set and reset. If the brake light is on, you have a break in the front or rear lines, or the parking brake is pulled, or the little valve in the block is stuck and gummed up. The only time this year light should go on, is when the park brake is pulled or you step on the brakes and the front or rear lines broke, as soon as you release the pedal the light should go off. Or someone put a real proportioning valve on the wrong year car.
1974 and onwards they have a real proportioning valve, that might need to be reset.
This is a brake failure block on 1968-1973. This valve can not restrict fluid flow to the front or rear.
How hard to I need to stomp on it? I pressed pretty hard on it will it was not running and also a few times with it was running. I pulled the switch and took a close look and did not see the low spot on the safety valve. So it has shifted off to the side out of site. The brakes seem to work fine and bleed fine. Really weird. I have the old proportioning valve out and can clearly see the low spot on the safety switch. If it doesn't center on it's own, I will likely need to take it out and do it manually. I now have a bleeder tool so hopefully it wouldn't happen again.
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Originally Posted by Peterbuilt
Depending on which way the valve moved:
Another way to reset the valve is to have a helper hold pressure on the brake pedal and open and close a front bleeder, if that doesn't work bleed a rear wheel
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74 Brake light
