Quote:
Originally Posted by ztim
I did some brake work and can't get the light to go off. I bled the brakes but am now worried I didn't do it enough. The brakes work just fine but it still drives me nuts. I need it to be safe.
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First, what type and year of Olds? Disc brake or drum on the front? I assume you're talking about the BRAKE light on the dash, correct?
If it is the dash light, first be sure you didn't accidentally touch the e-brake. The light will come on if the e-brake is not fully released (or if it's sticking or if the switch is cruddy). You can temporarily disconnect the brown wire from the switch on the e-brake pedal. If the light goes out, you've found the problem.
Assuming the e-brake switch isn't the cause, the other most likely cause is the differential pressure switch. All cars built since 1967 have separate front and back brake systems so that a leak in one doesn't cause a complete loss of braking. Follow the brake lines where they come out of the master cylinder down to the frame. There will be a brass or cast iron fitting where both lines go in and three other lines come out. If you have disc brakes, this is also the proportioning valve. There should be a single brown wire going to it as well.
Temporarily disconnect this wire. If the light goes off, this is the problem. (if not, you have a short someplace that's unrelated to the brakes). The differential pressure valve is a spool valve that is normally centered in the housing. If you loose pressure on one half of the brake system (which can happen when you bleed the brakes) the spool moves to one end of the housing, triggering the BRAKE light. Usually it comes back when you've finished bleeding, but it can get stuck due to crud in the valve. Which end of the car was the last one you bled? Crack a bleeder at the other end of the car while pressing on the brake pedal and the light should go out.