constant brake light on.

[vash]

ok, i have searched...ALOT!

everything says, disconnect this cable/wire for some specific time, and restart the car. i remembered reading this, and i did it. light goes off, but will come back on if i brake hard. (negative cable, for a few seconds). i read about JW positive cable for a few minutes. will try this when i get home. oh, and i can try the wire behind of the clock.

i havent driven my car for a long time so i cant really remember how things feel. but my car brakes fine, but the pedal is a tiny bit softer. and as i mention above, i got the light to come on in my driveway by pressing hard down on the pedal.

should i rebleed? did this 6 weeks ago before a track day. i need new pads? i will drive a car with all sorts of problems, but not brakes. i like stopping.

help
cliff

[Jubbie]

Are you talking about the dash brake light or the tail brake lights?

[vash]

oh, dash light.

thanks, never realized the double meaning!

cliff

[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. According to Warren, all US VW Beetles after 1966 used the same switch. The parts guy couldn't understand why I needed 2 of them.

Tom

[wholberg]

The brake light might be doing its job and letting you know that you have a small seal leak in the master cylinder that is going to get worse.

Try sitting in the car with firm pressure on the pedal for 5 clocked minutes. Ususlly, a small leak will allow the pedal to slowly go to the floor, and then you replace the MC.

[Early_S_Man]

Cliff,

Sounds like possible situation of one switch [on the master cylinder] sticking, and that would be enough, even if for only a few seconds, to cause the warning lamp relay to latch into the 'failed' warning situation!

Replace the VW switches ... they don't even have Porsche pn's. Inexpensive fix, I hope!

[acapella8]

This was the first fix to my p-car in August. Called my local autoparts and got them quick and cheap. (VW part as noted above) Toughest thing was remembering to reset the battery (remove cable) after the new switches were in. Because my light remained on until I did that.

[vash]

ok, really stupid que.

the switches are on the MC right? now where is the MC on my SC? on my 75 car is was a no brainer. it is behind that alum cover thing in the front trunk?

cliff

[petrolblue83911]

MC is behind the pedal cluster, you can see the top by removing the floor board behind the drivers floor mat. the access, you remove the floor board cover under the front axle, then you will be able to see it!

[vash]

ok, that wasnt that big a deal. i changed the switches, and went around a found an intermittent brake light coming and going. (will bum out, if that was the problem). for kicks i am gonna bleed it out tonight, to firm things up.

thank you to EVERYONE!

cliff