Brake Light sensor
 

Man, I step away from the computer for one weekend and I have a lot of reading to do. :D

Anyway, I had the opportunity to go out to SP this weekend for the SCCA corner workers school and was able to take the 911 out there, lots of fun even though I only took one lap for fun. During the evening, I did notice that when I hit the brake pedal, the lights do not come on right away. I have to be somewhat into the brakes before the lights come on. Is there a sensor down there that needs to be adjusted or replaced? Is this a DIY job or such a pain in the a$$ that it is not worth my time (I know that is blaspheme around here)?

Thanks.

Your symptoms are pretty typical of a bad sensor. The sensors are in the master cylinder and cannot be adjusted. Since there are 2 sensors, you don't know which one is bad and they are typically both replaced. Definitely a DIY job which sould take no more than 45 minutes if you have not done it before. A brake bleed afterwards may be necessary.

FYI: The threads on the sensors are tapered and WILL NOT thread all the way into the MC. Install them tight, but don't over torque....a good sense of feel is needed here. Over torquing the sensors will either lead to MC or sensor damage.

Did this during the last Tech on Linda’s ’87. More correctly someone did it for me while I watched. The sensors are on the master as CS says. The master is located on the inside of the power poster and requires removal of the carpet and cardboard cover to reach. From personal experience one goes bad then the others, is really why both need replacing at the same time. It helps to loosen the two air hoses for additional clearance. I think it was a 19mm socket for the senders. Very little brake fluid comes out but still you want to place a rag or paper towel under the fittings. You don’t need to bleed the brakes afterward but… I paid $20 each for the senders at the tech and was glade they had them in stock. Only real problem is reaching the senders, they are on the inside of the master. Helps if you climb into the luggage compartment.

As others have said, you need new brake light switches for the MC. I don't know if your MC is different than that of a SC, but I have a couple spare switches lying around.
Do not overtighten the switches, unless you want to replace your Master Cylinder. :lol:

Thanks for the info. I am going to look in my parts and tech reference manual for a PN as I looked on Pelican and Performance and couldn't a brake sensor other than the brake pad sensors. As I said I will look in the book for a PN. Any suggestions if it is not there? Pardon my green-ness. :oops:

It's called a "master cylinder brake lamp switch". look for it under master cylinder parts. Part # 113-945-515H
http://www.pelicanparts.com/catalog/..._pg2.htm#item6

D'OH :oops: That's why I'm smrt. Part of my edumacation was readn'. :?

Pari, big thanks :!: :!: for the info and the offer of your switches but as you can see, it looks like my car uses a two pole switch that came into use in '86.

Thanks again. :D

I did this on my old Carrera and got the switches from Olympus in Merrifield. They had them in stock for around $8 each. I think they were made by either VW or Bosch. Worked like a charm and the job took about 20 min.

I actually installed an adjustable version on the black racecar. That way I can get more or less sensitivity. Not really necessary but it works well. The switch I used is an adjustable fuel pressure sensor/switch designed for "NOS" (dude).