Just got a new master cylinder from PMB for my '73 1.7 and noticed the switch on the side of it has only 1 spade wire connector. My old leaky MC (original) has a 2 wire switch with a brown wire and a brown/white wire. Not knowing what I would do with the extra wire on the new single connector switch, I put the old 2 pole switch in the new MC. Now the big blinking red light on the dash gauge that tells you when the e brake is on no longer works.

Is the old 2 pole switch not meant to work in the new MC since it came with a single pole switch?

If I put the single pole switch back in in the MC will the brakes need to bled again since I opened up the brake system?

If I put the single pole switch back in, guessing the brown/white wire goes to the switch and solid brown wire (ground?) I can ground to some bolt near the MC?

I checked the brown/white wire with a test light while the ignition was on, and it did not light up. Should this wire have power with the key on?

Maybe the non functioning dash light is a wire problem and not the MC switch???

Looking for some help. Would appreciate the guidance. Thanks.

Ed

The new switches the brown is not needed as the part is grounded to the body. You can zip tie it neatly. Unfortunately, no one is making the two pole, and since the fix is easy, it's not worth the expense to tool up to make the correct version.

The single pole switch grounds thru the switch body and does not need a separate wire. With the key on you can jump the brown/white wire to ground to see if the light flashes.



That would likely be the switch at the hand brake lever and unrelated to the wiring at the master cylinder.

Ed,
Tried as suggested. Connected a wire from the brown/white wire at the handbrake switch and ran it to one of the seal belt bolts for ground. Ignition on, no red flashing light. Also tried same wire set up from the brn/white wire at the master cylinder with no results.
Maybe not doing this correctly???
Would a bad switch at the master cylinder be causing this condition at the red dash light?
EJP914

No... grounding either wire should put the light on. The wires from both switches come together at the connector for the light. Pull housing out of the gauge panel and check the bulb and wiring.

Did you push the little reset button on the master cylinder to reset that light?

Didn't know there was a red reset button on the MC.
Can you tell me where it is located?
Thanks!

Sorry for the reference to "red" button. Disregard.
Ed

On mine it is a little nub sticking up next to where the wires connect.