Fire under dash!

[schwaggen]

Started the car to pick up one of the kids, turned on the lights (which were on HI beam, clicked them to low) backed out of the garage, quickly noticed a burning smell - looked down to see smoke pouring out from under the dash/out the AC vent under the left end of the dash - Slapped the lights off, shut it off, I could see flickering light (flame) glowing on the floor -

Grabbed a flashlight, the flickering died, but the smoke continued - harsh smell of burning plastic/rubber - ran the the garage and got a fire extinguisher, but it was out- no visible damage, but car smells like ass - I can't get my head far enough back to see up/under very far- the wiring looks OK where I can see it- I'm guessing the light switch/relay itself?

Any ideas? Thanks in advance for your help. Leaving it in the driveway tonight, just in case. Close call- if I hadn't shut it off, or I had been out on the highway, this could have been BAD.

[mlfox]

If you haven't done so already, suggest you disconnect and isolate the negative battery clamp.

Regards,
mlfox

[schwaggen]

Done, thx.

[TRE Cup]

typically the headlamp switch shorts out internally. Start with that. With the battery disconnected, turn the dimmer and if it feels at all crunchy, that's it
second, crawl under the dash with a strong flashlite and look how extensive the damage
good luck

[86 911 Targa]

Originally Posted by schwaggen

Started the car to pick up one of the kids, turned on the lights (which were on HI beam, clicked them to low) backed out of the garage, quickly noticed a burning smell - looked down to see smoke pouring out from under the dash/out the AC vent under the left end of the dash - Slapped the lights off, shut it off, I could see flickering light (flame) glowing on the floor -

Grabbed a flashlight, the flickering died, but the smoke continued - harsh smell of burning plastic/rubber - ran the the garage and got a fire extinguisher, but it was out- no visible damage, but car smells like ass - I can't get my head far enough back to see up/under very far- the wiring looks OK where I can see it- I'm guessing the light switch/relay itself?

Any ideas? Thanks in advance for your help. Leaving it in the driveway tonight, just in case. Close call- if I hadn't shut it off, or I had been out on the highway, this could have been BAD.

If you did not blow a fuse, quite possibly one of your dash light wires shorted against the temp control sliders.

If so, here's what to do to prevent another occurence after you replace the harness:









If it is the headlight switch, you may well have incurred some type of damage to the stalk switch.

Also, if you have a M/Y 86-89, you should fuse the A/C condenser motor,footwell blowers, and the evaporator blower.

pm me as needed.

Good luck,

Gerry

[schwaggen]

Thanks guys- looks like I know what my Saturday plans are, now...

[Par911]

Timely thread, I just went through the same issue a couple weeks ago. Ordered a new switch from Pelican since mine was dead as a result. Nice pics and info. Gerry! Thanks.

[Creve]

Originally Posted by 86 911 Targa

If you did not blow a fuse, quite possibly one of your dash light wires shorted against the temp control sliders.

If so, here's what to do to prevent another occurrence after you replace the harness:

Also, if you have a M/Y 86-89, you should fuse the A/C condenser motor,footwell blowers, and the evaporator blower.

pm me as needed.

Good luck,

Gerry

Gerry, newbie here. I need a clarification on your last comment. Are you saying the same 3 amp fused wire also is needed for the blowers and condenser motor? A 3 amp wire like the one pictured for each? Also, what/where is the evaporator motor?

Thanks for the great pics!

Mark

[timmy2]

Evap motor is in smugglers box if you have AC.

[Daviboy]

Had exact same issues with my 82 SC a few weeks ago turns out was the lead going to the lights behind the ashtray, rubbed through shorted out and started melting and smoking like hell. It is an easy fix but a bit of a pain pulling the wiring then trying to get it all back neatly under the dash...

[dshepp806]

Originally Posted by 86 911 Targa

If you did not blow a fuse, quite possibly one of your dash light wires shorted against the temp control sliders.

If so, here's what to do to prevent another occurence after you replace the harness:









If it is the headlight switch, you may well have incurred some type of damage to the stalk switch.

Also, if you have a M/Y 86-89, you should fuse the A/C condenser motor,footwell blowers, and the evaporator blower.

pm me as needed.

Good luck,

Gerry

the '89 already has the footwell blowers and condenser stuff fused. The only thing I had to do to my 89 was fuse the dash lights. Rest was factory completed.

Best!

Doyle

[86 911 Targa]

Originally Posted by Creve

Gerry, newbie here. I need a clarification on your last comment. Are you saying the same 3 amp fused wire also is needed for the blowers and condenser motor? A 3 amp wire like the one pictured for each? Also, what/where is the evaporator motor?

Thanks for the great pics!

Mark

[Creve]

Originally Posted by timmy2

Evap motor is in smugglers box if you have AC.

Ah, that helps. Thanks! Also found out by searching that the footwell fuses s/b 10 amp.
Gotta do these mods soon! Fire seems to be my biggest fear what with all the unfused electrical connections and the aging fuel lines.

[Laneco]

Just a trick that helps in the dash area, pop out a couple of guages - gives you much more light and space to see problems.

Like the one shorted wire I found on my car. Fixed it and now it's "smoke free" - LOL!

angela

[schwaggen]

OK- so an update - dug around under the dash:

Def. found the SYMPTOM (see pic) Light switch is cooked WELL DONE/CHARRED.



As for the CAUSE- looked as best I could at the inst. light wiring- still haven't found where it might be shorted (if that's it...) The switch appears to be burned at the coil where the red/white wire brings the power in to the switch from the ignition switch.



SOMETHING pulled too much juice in, I just can't figure out what- no fuses are blown, and I can't find any burnt wiring under the dash or hood- it has to be something in the light circuits, though. Still looking.

I guess I'm replacing the wiring harness in this part of the car anyway. I looked at PP - don't see a part #?

Thanks for the advice and pics.

[scottb]

Time for a new switch (duh!). You prolly don't have to replace the entire harness in that area, but you'll definitely have to replace the connectors, and may have to extend the wires in the process. The trick will be to get matching color-coded wire. You may have to find a carcass in a salvage yard and cut out that section and graft it on to your car. Some people say mechanical (crimped) connections are better, and others like solder and heat-shrink tubing. Dave (TRE Cup), what's your preference for this kind of connection.

And now is the perfect time to add the fuse described above.

Good luck! Let us know how it turns out!

[shrtshck]

While you are working on the wiring, i'd recommend adding the headlight relay kit from PP. Took me about 30 minutes to install and eliminates full current running through the headlamp switch. At $25 (if memory is correct) it is cheap insurance.

Blair

[JFairman]

When my '87 headlight switch did something similar I got a nice '86 one from Rick at Weekend Rides for a good price. Used 911 Porsche Parts | Rebuildable Porsche Salvage | Weekend Rides
Give him a call he's a good guy.

Changed all the wires over one at a time and it works great.

[deshetlr]

My headlight switch fried. Many $1,000s later I have a new front harness. I will always replace the light switch on old Porches I buy in the future.

[schwaggen]

OK- After tracing as much wire as I could get to- I've come to the conclusion that the extra current running through the switch (no relay installed...YET) to the headlights (hi beams?) fried the switch.

New switch ordered- I could have saved a good bit of $$$ on a used switch, but given the postings above, it seems like I'd be asking for it to happen all over again with a switch of dubious origin.

The harness seems to be OK- I need to replace 3 or 4 of the connectors at the switch which got a little schmore'd, but other than that, it's all good. I need to suck it up and replace the dash lights with LEDs at some point- when I have a C note burning a hole in my pocket.

Have also ordered the headlight relay kit, which seems to get good reviews. Also bought a bunch of fuse holders/patches to do the inline fuses above- I need to look at the footwell blowers to see if they are already fused (mine is an '87) - One note- none of my blowers (hood vent, footwell) have ever worked since I bought the car- I guess this will be a good time to figure out why, exactly.