Bronze76

The brake light in my C3 is constantly illuminated. I have replaced the brakes and rebuilt the calipers at all four corners. The master cylinder level looks good in both reservoirs. The brakes function pretty well. I checked the parking brake switch and it is not the culprit. When I pull the wire off the proportion valve, the light goes off. In the not too distant past, the front calipers were leaking badly....so I am sure the brake light would have come on for that issue. But the brakes have now been repaired. Shouldn't the proportion valve switch automatically reset? If not, is there a way to manually reset it?

At this point, what is the most likely cause? Proportion valve or failing master cylinder?

Your advice is appreciated.

Thanks

Duke94

If you have a good solid pedal then the switch may be stuck closed. It should recenter (light off) with a good hard push of the pedal. If that doesn't work, pull the switch out and see if the switch plunger is stuck in the up position. While it's out, give the pedal another hard push. The switch is the white plastic part you see in the picture. Plunger is the silver part sticking out the bottom of the switch.

Bronze76

Excellent, Thanks for the help.

Is it safe to apply pedal pressure with the switch removed?

Duke94

Yes, there is no brake fluid in this cavity (if there is, the piston o'rings are worn out).

Bronze76

Ok, cool.
Thanks again. I will work on it this weekend and let you know what happens.

(I would never have thought to try this idea myself.....great to have forum help!)

Bronze76

A couple of hard stops did the trick!

Thanks again.