brake light switch

[catch2otwo]

When i step on the brakes in my 72 wag the brake lights do not illuminate. I looked at the brake pedal assembly and didnt see any kind of push button switch. I see two wires coming out of the bottom of the master cylinder. Is that some kind of pressure/hydraulic switch for the brake lights?

[mattywilz]

Take a look at your master cylinder, there should be a hydraulic switch threaded into the underside of it. You will have to bleed your brakes if you replace it.

[catch2otwo]

Take a look at your master cylinder, there should be a hydraulic switch threaded into the underside of it. You will have to bleed your brakes if you replace it.

Thats exactly what I thought that was. Do these usually go bad?

[oldyellowwagoneer]

Probably the factory switch so I guess they don't go out too often.LOL

[joe]

Thats exactly what I thought that was. Do these usually go bad?

In forty years? Yes. Changing brake fluid yearly as you should goes a long way to making the hyd parts last.

[lkmarsh]

My 69 had the same MC brake light switch. When it gave up, it not only leaked brake fluid, it let air into the MC. Plugged the hole and mounted a switch on the pedal, where it belongs. One example of bad design creating a completely unnecessary safety risk.

[catch2otwo]

My 69 had the same MC brake light switch. When it gave up, it not only leaked brake fluid, it let air into the MC. Plugged the hole and mounted a switch on the pedal, where it belongs. One example of bad design creating a completely unnecessary safety risk.

Any picture of the switch you used?

[blakeusa]

Just test the switch first using a test light - as it could easily be a bad ground or break in the wire or connector. It's a 2 wire switch and are used on many GM cars. Cheap part buy messy to replace.

I would remove the 2 wires bullet style connectors, clean the contacts and test first.

[catch2otwo]

Just test the switch first using a test light - as it could easily be a bad ground or break in the wire or connector. It's a 2 wire switch and are used on many GM cars. Cheap part buy messy to replace.

I would remove the 2 wires bullet style connectors, clean the contacts and test first.

Wow brain fart, I just realized that since my wheel cylinder has been leaking, my mc is empty. And since the switch is a pressure switch, there would be no pressure on the switch. I was just about to ask how to test it, and put 2 and 2 together.

[Revhendo]

Just test the switch first using a test light - as it could easily be a bad ground or break in the wire or connector. It's a 2 wire switch and are used on many GM cars. Cheap part buy messy to replace.

I would remove the 2 wires bullet style connectors, clean the contacts and test first.

Don't need a test light, the truck is already equiped with one. Just touch the two wires together and see if the brakelights come on.

Oh, and the pressure switch is more of a Ford deal. General Mayhem has been using pedal mounted switches for over 60 years.

[catch2otwo]

I will try connecting them two to see if I get power through the wire. Thanks

[catch2otwo]

OK so I unplugged both wires coming from the MC pressure switch. Connected them together. Put my test light on the wire and got nothing. To confirm, I turned on the headlights and the same wire became live.

Did I do something wrong or is my wiring fubard? My friend said the brake lights worked when he parked it so whats my next step? I looked at my jeep service manual but there was no wiring schematic.