brake problems..(warning light)

[fredsmedina]

In my '73 satellite, ever since I bought it, the parking brake warning light has been on.. I replaced the master cylinder and had a power flush done. So all brand new fluid in there..

What reasons are there that the brake light could be on? I'm thinking possibly it has something to do with a vacuum line or something?

Every once in a while, while I press down on the brake pedal, I'll see the light turn off for a quick second.

I have Power Brakes, disk front and drum rear..

All suggestions are helpful! thanks

 

[gtx69]

Have you tryed pulling up on the pedal .Spring could be badas pedal is not returning all the way up.

 

[68ChargerAG]

It sounds like a bad/broken/loose pedal return switch. The switch should only make contact (or take voltage to ground) when the pedal is pushed in. It seems like it might be shorting even when the pedal is out.

Try wiggling the switch.

Pedal might be pushing it too far also, see if it can be adjusted or tweaked to work properly.

 

[fredsmedina]

gtx69, i did try pulling up on it. .didn't do anything..

i'll go take a look at the pedal return switch right now..

but every once in a while, the pedal will go down too far, and the brakes dont feel as strong as they're supposed too.. which is sorta leading me to think that maybe there really is some sort of "problem"
i don't know..

 

[68ChargerAG]

I think that it is sounding more like an actual problem with your regular brake system. What is throwing everyone is that in your first post you said "parking brake warning light". Does the light actually say parking brake, or just BRAKE?

If it just says BRAKE I would say that you should look at the switch that is on the brake proportioning valve (in the engine bay down behind the steering box). I am not sure how that switch works, but maybe it is bad or unplugged. Or maybe it is sensing that your system is actually malfunctioning.

Maybe someone else can chime in and explain what that sensor does. ???

 

[68ChargerAG]

This got me curious because I am currently putting my car together and just installed these brake components. So I just looked into it a bit.

It looks like that switch tells you if there is a large pressure difference between the front and rear brakes caused by loss of brake fluid. If you are not losing fluid, maybe it is just telling you that your brakes need to be adjusted... or maybe it is just stuck.

Is the power disc brake system on you car stock, or was it an upgrade? If it was upgraded by someone they might not have used the correct proportioning valves and switch block.

Here is an interesting site on the switch and valve operation.
http://www.piratejack.net/troubleshooting/valveFAQ.htm

 

[Meep-Meep]

Pretty much like the above post says, the metering valve, or possibly in your case a combination valve, has a shuttle valve inside that triggers a contact when the fluid pressure is unbalanced in the system. Some cars are self centering and others (like my old 68 Mustang) are not and have to be manually centered. Try pumping up the pedal and have someone open a bleeder screw a tiny bit while pushing down on the pedal. The light should go out if you started with the correct side. If not, try the other axle. As soon as the light goes out close the bleeder screw.

 

[fredsmedina]

Pretty much like the above post says, the metering valve, or possibly in your case a combination valve, has a shuttle valve inside that triggers a contact when the fluid pressure is unbalanced in the system. Some cars are self centering and others (like my old 68 Mustang) are not and have to be manually centered. Try pumping up the pedal and have someone open a bleeder screw a tiny bit while pushing down on the pedal. The light should go out if you started with the correct side. If not, try the other axle. As soon as the light goes out close the bleeder screw.

This is my next step. I did some research.

I unplugged the ground hooked up to the propprtioning valve, and the BRAKE light trned right off. So I know that the problem is the prop valve. Just like you said, I'm going to "reset" the valve by bleeding them until the light turns off. will do that when I get a chance, and then i will update this post..

Thanks everyone for the replies! also got a ton of help on FABO