Master Cylinder Brake light switches...84 Carrera

[John Brandt]

My original MC has two prong connectors for the blake light switches.

The new one has 3 prongs.

however, the receptacle has what looks like a "Dummy Hole"
to accomodate that 3rd plug. It appears to me that I could plug the new 3prong connector into the original plug

what am I to do?

[911mot]

Fit it and see if it works

[scottb]

Where did you buy the parts? My recollection is that when I replaced mine a year or so ago, the switches were two-prong. You simply may have the wrong part.

Here's the Pelican catalog's description:

Master Cylinder Brake Lamp Switch, 2-Pole, 2 Req, 911/911 Turbo (1984-89) 113-945-515H $12.50

Good luck.

[BGCarrera32]

I know what you are talking about- I think I may have had to pull the wires from the connector to get hooked onto the correct terminals. The switch must have been updated somewhere along the line. Anyway they will work...sorry I can't be of more help. I recall doing this on my '84 when I changed the MC...anyway simple test as you'll either have brake lights or you won't when you hit the right connections.

Also ordered supposedly the correct part from Pelican and got the 3 prong switches.

-BG

[Jeff Alton]

Put the old switches in the new master cylinder. I can't tell if you bought a master cylinder of just new switches??

Jeff

[John Brandt]

I bought a whole new MC

the new one has 3 prong swithches old one has two

should I use locktite on them for a better seal if I swap them?


The thing is, I have a feeling that the the new 3 prong will fit and work, and I'd rather have new switches ideally.

[John Brandt]

My local wrench says that the 3 prong will work in the two prong connector. I hope he's right

[BGCarrera32]

Use the new switches. With these cars you can rest assured that 2 days after you install the new m.c. and get the brakes bled, you'll have a switch go bad. Then you'll get to start all over again...

[John Brandt]

That'd be hilarious if it weren't true.

[John Brandt]

Update... I had to put the old switches on the new master. I used a trace of blue locktite to seal them.

this job's sort of a PITA.

[armandodiaz]

Originally posted by John Brandt
Update... I had to put the old switches on the new master. I used a trace of blue locktite to seal them.

this job's sort of a PITA.

I'm doing this job right now, why did you end up using the old switches? Did you try to use the new switches? Did the new ones not work?

[Dennis Kalma]

There is a difference between the 3 prong and 2 prong switch set up. The 3 prong use a bit of clever wiring to turn on a dash warning light if one of the brake circuits fails, the 2 prong units don't do that (I think the warning light operates from the black box in the dash). Wiring wise they are the same, near as I can tell, but I would not use any locktite (unless blue is just a sealant) as the threads are actually tapered pipe threads which are basically self sealing. I would use a small amount of pipe goop (Permatex liquid teflon or similar) or just leave it dry. It will seal fine and I wouldn't want to do anything which makes removal more difficult, as you WILL be replacing them again. I am on my 4th set in 8 years....

Dennis

[John Brandt]

Thanks Dennis. That's good info for the archives. Thats exactly what I experienced. I used the blue loctite which is removable, and they sealed ok as far as I can tell.

My wrench was either mistaken or I misunderstood him....