Another Brake Warning light question??
 

I have a 76 turbo, dash brake light came on sometime last summer. Finally trying to fix it. Read thru the forum and gave it a shot. First I disconnected battery for a few minutes, light still on. Pulled wire off master cylinder, light still on. There's no mc reset switch. Took auto-climate control box off, Unbolted emergency brake unplugged wire to handbrake switch warning light, light still on. Took switch out hooked it back to wire nothing. What should I do next?

Did you disconnect the battery after removing the connectors on the master cylinder pressure switches? There is a latching relay function for the brake warning light associated with the MC switches.

Disconnecting the battery after replacing the MC switches worked for me;

I left it disconnected for about 10 min

I'm struggling with the same issue. First I checked the handbrake lever switch, then tried the battery disconnect and reconnect with the key on, then disconnected and reconnected the electrical connector behind the warning light, then disconnected and reconnected both of the the master cylinder pressure sensor electrical connections..........nothing seems to work.
My next thing is to buy new master cylinder pressure sensors...I've read that these can crap out or get gummed up and if the two switches are not in agreement, they throw the warning light.
Any other ideas out there?

As I understand the circuit, at least on my 77, if you disconnect the battery momentarily, and reconnect it and the brake warning light comes on when the key is turned on, then check to see if your brake lights are also illuminated. This would indicate that one of the MC switches is stuck on. If after reconnecting the battery the brake warning light is off and it illuminates when you press the brake pedal, then one of the MC switches is not operating correctly which could be the MC switch or a MC/brake issue. If its neither of these, it's probably something else associated with the brake warning light.

Mine kept Lighting up due to a loose bulb in the socket. Make sure they are in the holder nice and tight, mine would jar loose on bumpy roads.
Make sure both lights are working consistently and disconnect battery once you know they work.
Likely the pressure switches if not the lamps in the sockets.

I went through all the above then discovered this..

http://forums.pelicanparts.com/porsche-911-technical-forum/835893-parking-brake-light-always.html

Hope it helps,

Rahl

The ground wire that goes to the e-brake warning light switch. Does anyone know the path that wire take?. It looks like it travels between the seat belts and into the tunnel then I'm lost. Some help please.

Doesn't that go to the handbrake, to ground the light and make it come on? It is on a plastic adjustable plate to help keep the handbrake to switch in contact when raised (brake on position).

Rahl

Mine came on after an aggressive club run last weekend. Tried easiest fix first.

1. Disconnected negative cable from battery
2. Added about an ounce of brake fluid to master cylinder reservoir
3. Re-connected battery cable
4. Started car
5. Light off
6. Stroked the roof and praised the car for being a good girl!

'83SC... .....Love it when it's easy.

Rahl, that is the wire I'm talking about. The one on the handbrake. But where does it come from? If I want to backtrack the wire and look for a possible brake or pinch.

Brown/white wire for hand brake likely comes out of the through body harness behind the gauges/trunk area in a 2 Wire white connector that plugs in to the brake wiring harness back there.

Thanks, I will take a look int the trunk area.

My master cylinder only has one electrical switch and there's no reset on it. If I disconnect it and the dash brake warning light goes out than that's the problem. What if the light stays on could that switch at the mc still be the culprit somehow?