Brake light switch? '77s

[mykle57]

Hey folks need some help. Took the '77 911s for safety inspection this morning. Mechanic failed me for intermittent brake lights. (Sometime they work sometime they don't).

I pulled out the pedal board and I'm not finding the switch or any wiring down there.
Looked under the hood all around the master cylinder and I'm not seeing a switch there either.

Could someone give me a clue where this thing is for my model.

Thanks,
Mykle

[walt]

On the SC models its a dual pressure switch mounted on the brake master cylinder.

[seafeye]

If you have the earlier version you can take the switch out and adjust the arm so it’s more in contact with the large washer on the brake pedal. The switch can be sourced from the host here...
It’s very easy to test with an ohm meter. The two wires can go back on, on either terminal. So don’t worry about that. Do worry about dropping the screws getting it out.




Part #. 911 613 411 00

[mykle57]

There it is!
On the brake master cylinder, behind the booster, but, you got to remove the black trim piece to see it.

Thanks folks!

[spuggy]

Originally Posted by mykle57

Mechanic failed me for intermittent brake lights. (Sometime they work sometime they don't).

See you found them...

As the pressure switches get old/tired, they seem to slowly need more and more line pressure to activate - until they end up needing more than you'd normally use on the road to stop. Replaced a set a few years ago for the same reason myself.

I usually wait until I get a pickup or SUV with a big old chrome grille or bumper pull up behind at a red light, and check how much pedal pressure it takes for the brake lights to switch on.

It bothers me a little that I might be holding the brakes lightly at a stop - and thus showing no brake lights. And sometimes in traffic it's useful to show brake lights without necessarily braking significantly - eg to hint to the bozo behind you that maybe they should pay less attention to their phone because something's happening up ahead.

I intend to retro-fit the old-style micro switch to the pedal board.

[mykle57]

Having removed enough ancillary components near the brake booster, found the brake light switches. There are two. Thanks to those who replied!

Ordered a pair from our host; they arrived yesterday. And just before I was about to remove the existing switches, I thought hey isn't this going to leak brake fluid all over the floor of my trunk?

So, that's my question... Does removing the brake light switches allow brake fluid to leak out?

[brockperry]

Originally Posted by mykle57

Having removed enough ancillary components near the brake booster, found the brake light switches. There are two. Thanks to those who replied!

Ordered a pair from our host; they arrived yesterday. And just before I was about to remove the existing switches, I thought hey isn't this going to leak brake fluid all over the floor of my trunk?

So, that's my question... Does removing the brake light switches allow brake fluid to leak out?

Just a few drops from front switch on my '85 911. This thread helped me on it last week:

Help, No brake lights

[Satanas]

You can also connect an electrical microswitch parallel to the 2 pressure switches.

https://translate.googleusercontent.com/translate_c?depth=1&nv=1&rurl=translate.google.fr&sl=auto&sp=nmt4&tl=en&u=https://www.type911.org/blog/%3Fidmembre%3D150&xid=25657,15700021,15700186,15700190,15700256,1570 0259,15700262&usg=ALkJrhjVQeao9z50odvhvTpqGCvlh1XpYw

[mykle57]

It was a bit of a chore to get a socked in there, but, new switches are installed and I've now got a passing inspection sticker.

Thanks a bunch!

[mykle57]

It was a bit of a chore to get a socket in there, but, new switches are installed and I've now got a passing inspection sticker.

Thanks a bunch!