Break light wiring

[bsimonson]

I noticed recently that my break lights does not work at all. After looking through the wiring I found the following:

1. The wire from the fuse was not connected but routed to the break light switches. In the wiring diagram in the Bentley manual it said to connect it to fuse 15 (8A), only fuse 15 it not 8A, but 16A (according to the fuse overview, page 971-2). So now I'm unsure on where to wire it to, any ideas?

2. After making a temporary wire to the switches with a 8A fuse they were powered correctly, but when I connected the grn/blu with the blk/yel to simulate breaking the lights still did not light up. Following the blk/yel wire it was routed (correctly) to the cruise control unit but nowhere else. It is supposed to also connect to a blk/grn wire and then on to the break lights. Looking a bit around the break servo I found one loose connector with a blk/grn wire. Is that where the break light switch connects to the loom? I did try to measure connection from that connector to the rear right light connector by the engine mount but got connection on all wires in the back so not sure what that indicates.



3. The black wire to the brake/belt warning was also not connected, but that shouldn't affect the lights, right?

Cheers, Björn

[86 911 Targa]

Originally Posted by bsimonson

I noticed recently that my break lights does not work at all. After looking through the wiring I found the following:

1. The wire from the fuse was not connected but routed to the break light switches. In the wiring diagram in the Bentley manual it said to connect it to fuse 15 (8A), only fuse 15 it not 8A, but 16A (according to the fuse overview, page 971-2). So now I'm unsure on where to wire it to, any ideas?

2. After making a temporary wire to the switches with a 8A fuse they were powered correctly, but when I connected the grn/blu with the blk/yel to simulate breaking the lights still did not light up. Following the blk/yel wire it was routed (correctly) to the cruise control unit but nowhere else. It is supposed to also connect to a blk/grn wire and then on to the break lights. Looking a bit around the break servo I found one loose connector with a blk/grn wire. Is that where the break light switch connects to the loom? I did try to measure connection from that connector to the rear right light connector by the engine mount but got connection on all wires in the back so not sure what that indicates.



3. The black wire to the brake/belt warning was also not connected, but that shouldn't affect the lights, right?

Year and model please.

[bsimonson]

It's a 1980 911 SC.

[80-911SC]

check the brake light switch at your master cylinder, your problem sounds just like mine .... a ten dollar part .......

[86 911 Targa]

Originally Posted by 80-911sc

check the brake light switch at your master cylinder, your problem sounds just like mine .... A ten dollar part .......smilewavy

+1

[tcar]

Bjorn, usually spelled 'BRAKE', but I guess if it broken, it could be 'break', also.

Nine dollar part.

Porsche 911 & Carrera Brake Hydraulics - Page 3

[bsimonson]

Originally Posted by tcar

Bjorn, usually spelled 'BRAKE', but I guess if it broken, it could be 'break', also.

Nine dollar part.

Porsche 911 & Carrera Brake Hydraulics - Page 3

Haha, of course. Guess that went under the spell check radar.

Anyway, as much as the brake light switch could be broken there has to be another problem as well. I'm not sure I gave a clear description above, but I did bridge the switch to get it out of the equation. My main problem is that I don't know where to wire in a new wire from the brake switch to the brake light loom (should be blk/yel according to the Bentley manual).

What I would really need is for someone to trace their black/yellow wire from the brake switch until it goes into some kind of connector and tell me where I can find that (or post a picture).

Cheers, Björn

[bsimonson]

I've done some more reading on here and found the pelican wiring diagram for the brake light circuit, http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_Part3-1.jpg.

So, what I'm looking for is the T2f connection as I suspect that these wires have been tampered with at some point and that whoever did it forgot to wire the switches to the brake lights (the bk/ye wire from 81 on the switches only run to the cruise control unit).

Does anyone know where that connection is actually at in the car (and what it looks like)?

Cheers, Björn

[bsimonson]

I spent some more time working on the brake lights the other day and could verify that the contact I first thought it was (see picture above) indeed is the connector to the brake lights. Wiring the brake light switch to the black/green wire made the lights come on when I press the pedal.

What I learned was that if you want to measure for connectivity to the rear lights, you need to disconnect both left and right connectors or otherwise they are grounded and the measurements will be inconclusive.

[tcar]

If you do the brake light switch, do them both (there are 2).