69 Buick Wildcat brake warning light

[CT Car Guy]

I am working on a 69 Wildcat just out of long term storage. The brake waring light stays on. I also noted that the right stop light stays on all the time. I checked the 4 way and the left bulbs are good. The warning light has been on since I bought the car and took it out of storage. The rear master cylinder was empty. I put fluide in and put the car back into storage. When I got it out, the master was still full.

I pulled all of the drums and there are no leaks. I did a front brake job since it needed it. Adjusted all the brakes. I pulled the wire off the distribution block and the light stayed on. I will check the ebrake.My question is why would the right stop light stay lite with the car in park and no pressure on the brake pedal. The pedal feel firm. Ideas?

[Guest brh]

Brake warning light could be as simple as the parking brake on?? As for one of the tail lights being on, I suspect a bad ground on a socket or a wrong bulb installed in a tail light... 1056 instead of a 1057. Check all your bulbs to make sure they are correct.

[NTX5467]

Seems like the brake light in the instrument cluster could serve double-duty as the warning light for fluid loss in one (front, rear, both) or both of the fluid circuits AND for the parking brake being applied.

The parking brake circuit is a simple contact switch on the pedal. If the contact is not made, the light's circuit completes through the warning light on the instrument cluster. Or is could be the other way around. But the whole issue is whether the electrical circuit is "made" or "broken" . . . either at the official contact point or with a broken wire.

The fluid circuit switch is IN a brass block just below the master cylinder (basically). If the contact is moved off-center in the housing, it lights the light. Having a fluid bias (to one circuit or the other) makes the contact move off-center and light the light. In other words, it's NOT a simple "I've got fluid" sensor switch, but a mechanical contact situation. It might be necessary to vacuum bleed the section of the brake system which had the low fluid situation. Vacuum bleed AT the master cylinder rather than at the wheel cylinder end.

"Vacuum bleed" is how the fluid is put into the system at the factory. A plate/seal situation is placed on top of the master cylinder and a vacuum applied to the system. If the vacuum holds (meaning "no leaks"), then the fluid is put into the system at the master cylinder. You might find something to do this "in the field" at an automotive tool supplier or fabricate something with an old master cylinder cap and a hand vacuum pump. You might have put fluid into the master cylinder, but there could well be an air pocket lower in the system.

When changing master cylinders, I've had decent luck with putting fluid into the master cylinder with the lines firmly attached. Then, I'd push the brake pedal in shallow and QUICK pumps to alternately pressurize and "no pressure" the system. In many cases, any air bubbles in the bottom of the cylinder and the top of the lines will generally significantly purge themselves at that time . . . at least enough that the vehicle is usually safe to drive in traffic. But I'll usually take it easy until the fluid level stabilizes, just to be safe. That's how it's worked for me . . . your experiences might be different . . . proceed at your own risk.

When you fill a master cylinder with an empty section, you'd expect the brake fluid to flow into the smallest cavities of the lower part of the cylinder, where the pistons and such are, but that usually does not happen. This is why the vacuum bleed or the home-grown action is needed to get all of the air from the system. It also keeps any air pockets/bubbles localized at the top of the system . . . where they'll probably gravitate to anyway, with time . . . rather than pushing them through the lower part of the system with pressure bleeding. Also, in many cases, the air bubbles which come up from the bottom are about the size of the fluid feed hole in the bottom of the reservoir, as if that's the smallest they can be in that sort of fluid.

Just some thoughts,

NTX5467

[CT Car Guy]

Problem solved. The warning light was because the ebrake spring had broken and the "spring" used was too long. The problem with the one brake light staying on is due to a problem in the turn signal switch on the steering column. Who carries replacements?

[NTX5467]

Turn signal switches might be as close as your local chain auto supply. A quick look on RockAuto Auto Parts reveals that the main issue is "With" or "Without" cornering lights.

It also seems that that particular switch was used from '69-'76 on a multitude of GM cars and other non-GM makes that used a Saginaw steering column (AMC, Jeep, for example). Full-size GM and mid-size (including "muscle cars", with further guarantees it's availability in the future, typically) GM cars.

I suspect they all come from the same factory (in different boxes), so you can price shop some, if you desire -- just my gut suspicion. RockAuto Auto Parts has pictures of the connectors, too, so you can compare color codes and placement in the plug-in connector.

Enjoy!

NTX5467