Brake Warning Light...confirm my suspicion

[deguitars]

'82 SC brake warning light came on but nothing unusual about the brakes themselves. Brake fluid flush about two years ago. Checked the fluid level and what do you know, down to about 1/2 capacity. No obvious leaks but it had to go somewhere, right? So my guess is a leaky master cylinder dumping into the servo?. Boy does changing out the MC look like a fiddly fart of a job. I've done plenty of brake work on other vehicles but anything I should know about the SC ahead of time?

Cheers

[emcon5]

There is a warning system built into the brake light switches in the master cylinder. There is some extra wiring that will light the parking brake warning light if the 2 switches are not in agreement. The theory is a warning if you have a failure in one of the 2 circuits, front or rear. In practice, it is a warning that one of your switches needs to be replaced (well maintained brakes don't fail that often).

The switches can get gummed up from old nasty brake fluid, and stick. I replaced mine with VW switches. There was an old thread where Warren (RIP, Early_S_Man) mentioned all US VW Beetles after 1966 used the same switch. The parts guy couldn't understand why I needed 2 of them.

[emcon5]

Forgot to mention, the brake fluid could be low simply from worn brake pads. As the pads wear down, the pistons are farther out in the calipers, and more fluid is in the caliper.

How old are your pads?

[deguitars]

Thanks for your input. I thought of the pads but they were replaced at the time of the flush, only about 4K miles ago and still look basically new. The fluid level appears to have gone too much for that to explain it.

cheers

[emac]

Your probably leaking inside the car and behind the pedal cluster. Check your carpet good chance it's wet from the MC. The only thing I can say about replacing it is it's a PITA! But then again I'm 67 so I don't bend as I used to
Ernie 81 sc

[emcon5]

Funny, took my car out this afternoon, and the brake light stayed on.....

Something to remember, there is no low fluid warning in that light in a SC. The light being on is not caused by the low fluid.

The light stays on for the reason I mentioned above.

[timmy2]

Warning lamp will also come on and stay on (latched) from a burnt out tail light bulb (or loose in the socket too). Stays on until you disconnect battery cable to unlatch it.

[deguitars]

Thanks for the replies. I should have mentioned I've pretty much checked through the usual suspects for things that might cause the warning lamp to come on, and been through the disconnect the battery routine, etc. My bigger concern is the disappearing brake fluid. I'll have to take a look at the car this weekend and see if there are signs of fluid leaking in the interior. I ran my hand under the servo quickly the other day and didn't feel anything but I wasn't trying too hard.

Since it came up, is there or isn't there a low brake fluid sensor in a '82 SC? I can't find one.

cheers

[Jesse16]

If you don't see a sensor in the reservoir cap, then there isn't one. Right " My 87 has/had wires to a float switch in the cap but it didn't work when I bought the car 10 years ago and I'm OK with that.
My car also had the sensors in the pads, also not functional so I removed all that junk. Car leads a privileged life of over maintenance so those kinds of nannies are a nuisance. I'm lucky the warning lights inside also appear to not work.

[emcon5]

Repeating:

Originally Posted by emcon5

Something to remember, there is no low fluid warning in that light in a SC. The light being on is not caused by the low fluid.

Originally Posted by deguitars

Since it came up, is there or isn't there a low brake fluid sensor in a '82 SC? I can't find one.

[bugstrider]

chased this gremlin around until I changed out both brake light sensors on the MC, rather inexpensive job and....... problem solved.

Cheers