Master cylinder warning light question

[lopena]

Attached is a photo of the MC on my '69 911S. As you can see, the brake fluid warning light switch has seen better days and is not connected to the two wires nearby. My questions are:

- the switch has only one terminal but there are two wires. Can I assume that this is a replacement MC that came with a single terminal while the original factory MC had two terminals?

- assuming two terminals are correct, does the switch connect the two wires together when there's a loss of brake fluid? Alternatively, does the switch connect the two wires to ground if there's a fluid loss?

- if I try to replace the single-pole warning switch with one that has two terminals I assume I'd have to subsequently bleed the entire braking system to eliminate any air, correct?

Any help is much appreciated, as always.

Alan

[Davz912/911]

Alan,

I want to say that's the "brake light" switch. A low fluid switch would be a float in the reservoir.
Some switches are single pole, others two. My 67 tho has a switch above the brake pedal.
just my 2c...I've been known to be wrong.

Dave

[edmayo]

Does your handbrake warning light work?

[lopena]

Yes, my handbrake warning light and brake lights all work.

[edmayo]

Then don'T worry about the wires, that is to tell you that you'be lost fluid in one circuit. You'll know when that happens.

[Richy]

Connect the brown wire with the white stripe to the terminal . The switch provides continuity to ground when fluid is low in either the font or rear lines creating an imbalance that moves a rod that triggers the switch . The e-brake light will now stay on . The switch has to be reset by pushing on the small white plastic rod in the center when this happens . Sometimes this happens when bleeding brakes .,

[SIMI BOB]

Original equipment was a switch with two spades. Replacement M/C comes with switch with one spade.
Bob B

[lopena]

Bob:

Yes...since I have two wires it seems logical that the original MC had two spades. So, does this mean that the switch would connect the two wires together when fluid was low?

[SIMI BOB]

lopena,
See Richy's reply above. I looked at the schematic but couldn't figure out where the switch was, but I assume that one of those wires is ground, and the other goes to the light. Follow Richy's advice above and it should work.
I assume that from the factory, the switch was provided with a ground wire, but later on the switch was grounded internally, so only the wire to the light is necessary.
Bob B

http://www.pelicanparts.com/911/911_...l_diagrams.htm

[71gold]

Want to revive this thread.....
Several questions ....

My harness has 2 connectors and the MC has one spade with a small plunger .
Why not replace the switch to a 2 spade ?
There must have been a function for both spades?
Not sure I understand the logic of forgetting about the other connector.
Also What actuates the plunger
Thanks for info
Frank