1970 PORSCHE 911 Targa Brake Warning Light

[Juloping]

Okay. Understood. I will try to do that this afternoon or tomorrow morning because I have a complete E-Type IRS unit to get in back before ! Thanks

[Juloping]

Edmayo,

The master cylinder switch is definitely the part #40 on the wiring diagram ! Thanks. When I disconnect it, the handbrake warning light at the dashboard turns off. I tried to move forward and backward the little button in its centre but it seems to be stuck ! The problem probably can from here.

Just a question, this master cylinder switch gets only one connector but :
# All the switches found on the web for this 2.2T US 911 gets 2 connectors
# My car has 2 wires which go to this switch, even if only one was used

So what do I do ? Do I try to find a brake master cylinder switch with one connector or do I purchase a 2-connector switch and connect on it my 2 wires ?

[Juloping]

"The problem probably comes from here" and not "... can from here" !! Sorry

[edmayo]

The original switches were two pole for U.S. cars, replacement master cylinders only come with a single spade switch, either use the old one or use a piggy back spade connector to use both both wires. You PUSH the button in to reset it. Use an ohm meter and test from the spade to the metal base, it has to be an open circuit, when you bled the brakes the piston moved further and tripped the switch. If you can't get an open circuit replace the switch.

[CheckBookChuck]

I just went through this with my '71 911T.

The hand brake switch was broken. I replaced it and the light still blinked.

Removed the two wires on the MC Switch and light went out.

Removed the MC Switch, pulled out the piston (two pole switches do not have a reset button on the outside), did some measuring and established that the activation piston in the MC was pushed to one side illuminating the switch.

Re assembled the switch, and bled the brakes (with the ignition OFF!).

Presto! all good now.