Smoke from under dash

[brighton911]

We were backing out of the garage and then the smoke rolled out from under the dash. On the passenger side the was a small gauge brown wire with all the insulation melted off. Funny thing, no fuse had blown and everything on the car still worked, well except for the interior lights. Turns out both sides of the wiring from the door switches into the main harness were totally melted and I'm sure the same goes for in the harness. Now what I don't understand is, the door lights are grounding type contacts and with the doors closed, there would have been no ground at the time of the smoke. Now even better, even though the insulation is gone off the wires, if I ground them, the light will come on.
So, the plan is to cut open the main harness and find out if there is any other damaged wires and replace as necessary. Anyone have any suggestions as to a cause and do you agree with opening the harness? I know it won't be a fun job, not sure if it will be from the firewall side. Thanks!

[crustychief]

What year is the car?
The interior light circuit is usually combined with another circuit, for instance the 85 interior lights also have the clock.

[glennspiegler]

Many 911s including my 88. The interior lights are unfused. I followed an article from this site doing a small in line fuse upgrade to prevent this from happening. Would rec pulling steering wheel and all guages to really have access. Good luck, Glenn

[dshepp806]

Without question, once repaired, do get the unfused circuits to a FUSED state...it's a simple mod and worth avoiding your experience.

Best of luck to you!

Doyle

[80-911SC]

I guess fusing my interior lights is now on my to-do list ....

Already did the relay and fuse to the headlights ...

Any one care to chime in on which other circuits need attention ....

Thanks Steve

[86 911 Targa]

Originally Posted by 80-911SC

I guess fusing my interior lights is now on my to-do list ....

Already did the relay and fuse to the headlights ...

Any one care to chime in on which other circuits need attention ....

Thanks Steve

Steve,

Here you go, I posted this a while back:

Added fuses and relays:


3A dash lights fuse from "The Boys".








8A front condenser blower motor fuse from "The Boys".


15A Fused evaporator relay from our host.

Good luck,

pm me as needed.

Gerry

[80-911SC]

Gerry .. you are the man ... thank you .. again you have the answer to the question ... and even better I have two of those inline fuse holders in the electrical drawer on the roll around ... I will make quick work of that on night this week ..

Thanks Gerry ...

Since we have your attention any other doses of wisdom ??

I did the relay on the headlights per one of your earlier threads .. did the 4 relay option so each beam and light has its own .. also I think it was one of yours for the turn signal switch clean up for the contacts ...

But any other recommendations you have are appreciated ...

Steve

[jpahemi]

The fuse added to the light switch also covers the lights in the gauges??

Regards,
jp

[86 911 Targa]

Originally Posted by 80-911SC

Gerry .. you are the man ... thank you .. again you have the answer to the question ... and even better I have two of those inline fuse holders in the electrical drawer on the roll around ... I will make quick work of that on night this week ..

Thanks Gerry ...

Since we have your attention any other doses of wisdom ??

I did the relay on the headlights per one of your earlier threads .. did the 4 relay option so each beam and light has its own .. also I think it was one of yours for the turn signal switch clean up for the contacts ...

But any other recommendations you have are appreciated ...

Steve

If you have pre-'87 footwell blowers:




10A fuse.

And, I reduced the current draw of fuse #2 (A/C) by re-routing the
front condenser fan load to fuse #3.

Fuse #2 has had a history of overheating due to high current loads/corrosion.

On the 3.2 cars fuse #2 is only used for the Cab folding top,
and the headlight washers.









And, for the foglights.

This will alllow you to run the foglights independent of the headlight switch:






As for the headlight relays, I installed the JWest units which has one relay for the low,
and one for the high beams.

Note: Be sure to document any electrical wiring modifications for the next owner, or your mechanic.

pm me as needed.

Good luck,

Gerry

[80-911SC]

Thanks Gerry ...

[brighton911]

Thanks for the wonderful detailed responses from everyone. The wiring diagrams are exactly what I needed, couldn't find the appropriate ones in Bentley. I was really surprised there would be unprotected circuits, someone wasn't thinking that day. For sure I'll be adding fuses/protections where needed. Oh, and by chance, my car is also an 86 Targa. Dave

[Dublinoh]

Sorry, little slow here. If I fuse the dash lights that will take care of the other interior lights?

And where is this? Is that the light switch next to the Key on the left dash?



Does the knob just unscrew to remove?

[airbil]

That IS the headlight switch removed from the dash. Unscrew the knob and the black plastic threaded flange with four little holes that is behind it. If the flange will not move, reach behind and try to unscrew/loosen the switch assembly behind the dash until you can unscrew the black plastic flange. The headlight switch can then be pulled backwards and allowed to hang down.

And while we're talking about this area behind the headlight / hazard switches..., could someone tell me what this lone grey wire sprouting downwardsout of the turn signal assembly is?
Thanks very much!

[86 911 Targa]

Originally Posted by airbil

That IS the headlight switch removed from the dash. Unscrew the knob and the black plastic threaded flange with four little holes that is behind it. If the flange will not move, reach behind and try to unscrew/loosen the switch assembly behind the dash until you can unscrew the black plastic flange. The headlight switch can then be pulled backwards and allowed to hang down.

And while we're talking about this area behind the headlight / hazard switches..., could someone tell me what this lone grey wire sprouting downwardsout of the turn signal assembly is?
Thanks very much!

For our '86, that's a 1mm grey wire from connection #d on the turn signal switch,
to ignition switch connection #o.

Here's a link for the earlier cars:

http://www.cannell.co.uk/

Good luck,

Gerry

[groovzilla1959]

one of my 1st 911sc's had an issue with the headlight fuse - i used some aluminium foil and wrapped the headlight fuse - worked great until smoke started pouring out from under the dash - complete wiring harness had to be replaced.

lesson learned the hard and expensive way!

[airbil]

Thanks Gerry!
I'll check this out.

Originally Posted by 86 911 Targa

For our '86, that's a 1mm grey wire from connection #d on the turn signal switch,
to ignition switch connection #o.

Here's a link for the earlier cars:

Rick's Cars - www.cannell.co.uk

Good luck,

Gerry