911SC missing power to interior electric components. How to get started?

[esbensjensen]

Hi,

After a lot of reading, this is my first post. Excited to be part of the forum! 🙌

Since I bought my 911 SC (from 1979) last year, I've been trying to figure out how to deal with these components, that won't turn on, and seems to be on the same wiring:

- interior cabin lights
- cigarette lighter
- radio
- frunk light
- clock (is not running)
- odometer (not running)

I have a wiring diagram of SC's from 78/79 and I've checked fuseholder 18, which unfortunately only have one wire mounted, meaning one is missing (see photo).

I've read a lot, but I don't have a lot of experience with electrics. I don't get how to get started. How do I find the missing wire(s) to connect? Do I have to split all dash etc apart or can I open something in th frunk to get more access?

Any help highly appreciated 🙌

[esbensjensen]

[GH85Carrera]

I have an 85 911, so it might be different. On my car if you look at the little white in-line connector near the bottom of the photo, that was my issue. It is a connector that supplies power to the components you mentioned. I suspect it was a connector the factory put in to allow a mechanic to separate, and kill the interior lights and the trunk light during maintenance if the doors or the trunk were left open. I had to replace my connector to get everything functional.

[esbensjensen]

Originally Posted by GH85Carrera

I have an 85 911, so it might be different. On my car if you look at the little white in-line connector near the bottom of the photo, that was my issue. It is a connector that supplies power to the components you mentioned. I suspect it was a connector the factory put in to allow a mechanic to separate, and kill the interior lights and the trunk light during maintenance if the doors or the trunk were left open. I had to replace my connector to get everything functional.

Thanks for the response seems I also have a connector, though it doesn't seem to be the problem - "A" on the Pic below.

My challenge is that fuse no. 18 (marked with green in the first Pic) is only connected with a wire at the top, but not at the bottom. How do I get started on finding the wire to connect? Is there a smart way of finding wires? Or checking for instance the capped connector "B", without risking frying my electric setup?

[GH85Carrera]

That A is not the same wire as my car. It is a single connector. Inside the cover for the fuse box is a label built into the plastic. It list what fuse powers what.

One common issue for thees cars is previous owners have replaced a fuse with a plastic core fuse and aluminum connector. They are common at the local parts store.

Do a search on Amazon for a "ceramic core bullet fuse" and find one that uses copper for the contacts. Replace all the fuses after a slight cleaning of the contacts of the fuse block. It will prevent a lot of issues in the future, and may fix your issue. The last time I called Pelican about the fuses they sell they were the junk plastic core fuses. Those are useful only to gt you back home and need to be replaced asap.

[boyt911sc]

Originally Posted by esbensjensen

Hi,

After a lot of reading, this is my first post. Excited to be part of the forum! ��

Since I bought my 911 SC (from 1979) last year, I've been trying to figure out how to deal with these components, that won't turn on, and seems to be on the same wiring:

- interior cabin lights
- cigarette lighter
- radio
- frunk light
- clock (is not running)
- odometer (not running)

I have a wiring diagram of SC's from 78/79 and I've checked fuseholder 18, which unfortunately only have one wire mounted, meaning one is missing (see photo).

I've read a lot, but I don't have a lot of experience with electrics. I don't get how to get started. How do I find the missing wire(s) to connect? Do I have to split all dash etc apart or can I open something in th frunk to get more access?

Any help highly appreciated ��

A quick look at the Factory Shop Manual (Vol. VI) shows the following:

• Cabin lights, W1, circuit #45 & #46, fuse #18.
• Cigarette lighter, U1, circuit #61, fuse #15.
• Radio
• Trunk light, W3, circuit #42, fuse #18.
• Clock, Y, circuit #40, fuse #18.
• Speedometer, G1, circuit #70, fuse #13.

There is only one (1) black wire connected to fuse #18 outlet. You could use either a 12-volt automotive test light or the fancy electronic test light that tells you if the line is +/- or a multi-tester. A copy of the colored wiring diagram will help you trace the missing wire/s. BTW, what is that glassed fuse beside fuse #18?

Tony

[esbensjensen]

Originally Posted by boyt911sc

A quick look at the Factory Shop Manual (Vol. VI) shows the following:

• Cabin lights, W1, circuit #45 & #46, fuse #18.
• Cigarette lighter, U1, circuit #61, fuse #15.
• Radio
• Trunk light, W3, circuit #42, fuse #18.
• Clock, Y, circuit #40, fuse #18.
• Speedometer, G1, circuit #70, fuse #13.

There is only one (1) black wire connected to fuse #18 outlet. You could use either a 12-volt automotive test light or the fancy electronic test light that tells you if the line is +/- or a multi-tester. A copy of the colored wiring diagram will help you trace the missing wire/s. BTW, what is that glassed fuse beside fuse #18?

Tony

Thanks, that's very helpful. What does it say in terms of the radio connection? I haven't been able to find out where it is supposed to be connected anywhere.

Which function/how should I use on my multi-tester? I have colored wire diagram, but I'm still confused how to practically get started on tracing wire(s).. Do I need to split the wiring tape and pull everything apart from the fuse panel or is there a smarter way?

Unfortunately no clue about what the glass fuse is handling 🙈

[esbensjensen]

Originally Posted by boyt911sc

...There is only one (1) black wire connected to fuse #18 outlet. You could use either a 12-volt automotive test light or the fancy electronic test light that tells you if the line is +/- or a multi-tester..

Tony

Unfortunately, I'm missing the black wire connecting in to my fuse 18. I only have a red wire connecting at the top. I can't figure out how to test/trace/find it

[esbensjensen]

Originally Posted by GH85Carrera

That A is not the same wire as my car. It is a single connector. Inside the cover for the fuse box is a label built into the plastic. It list what fuse powers what.

One common issue for thees cars is previous owners have replaced a fuse with a plastic core fuse and aluminum connector. They are common at the local parts store.

Do a search on Amazon for a "ceramic core bullet fuse" and find one that uses copper for the contacts. Replace all the fuses after a slight cleaning of the contacts of the fuse block. It will prevent a lot of issues in the future, and may fix your issue. The last time I called Pelican about the fuses they sell they were the junk plastic core fuses. Those are useful only to gt you back home and need to be replaced asap.

True, the connector seems double. Maybe difference between '79 and '85..?
Yeah, I'd like to get ceramic fuses, but haven't gotten them yet. For now I just cleaned contacts, as I only have the plastic/alu at the moment.
Still seems a bit to me, that the challenge overall, is a missing wire issue?

[boyt911sc]

Originally Posted by boyt911sc

There is only one (1) black wire connected to fuse #18 outlet. You could use either a 12-volt automotive test light or the fancy electronic test light that tells you if the line is +/- or a multi-tester. A copy of the colored wiring diagram will help you trace the missing wire/s. BTW, what is that glassed fuse beside fuse #18?

Tony

Start your investigation from load to source (fuse). For example:
CLOCK………….Look behind the clock for a black wire. If there is no existing black wire connected at the backside of the clock, search under the dash. It might had been disconnected. If this black wire does not exist, you got bigger problem to tackle.

If I were in your shoes, I would be very curious to know what that glassed fused is doing there. There is a very likelihood it could be the missing black wire(?). Good luck.

Tony

[Ngrich99]

I have a 1979 and everything works and I assume it’s OEM. I tried to post pics but site is not cooperative. Let me know if I can help with pics or reference.