Mark SF

I just took the beast for a 100 mile run, over to the coast, up highway 1 and back. Ran great and without a hitch, until 1 mile from the house.

Smoke started pouring out of the headlight switch. I turned them off quickly, and limped home on the sidelights which still worked.

When I got home the headlights were not working. I put my spare headlight switch in, and everything's fine. Headlights work, switch doesn't get hot.

What gives? Intermittent short? Faulty new headlight switch? Is there a lot of current going through the switch?

Nicole

Was that smoking switch brand new? Do you see where it fried, or can you tell by the smell?

Mark SF

Yes, it is a brand new switch. I just took it apart, and it looks like the contacts to the little light bulb have shorted out. The bulb has disappeared.

So I suspect that at some point in the drive the little light bulb worked it's way out, allowing the contacts to short.

928mac

I guess the next question would be was the switch aftermarket or a porsche part?

Mark SF

Same thing - it was described as "OES" and has a Porsche part number on it.

Mark SF

The good news is that on the 100 mile drive with a pretty complete mix of driving : some hill climbing, a few full throttle spurts, and cruising at 70-80 on the freeway, I got 19mpg. Car seems to run better every time I drive it. Maybe it's the techron I'm putting in every tank at the moment?

Didn't even have to top off the oil or coolant afterwards.

Dave928S

What do you mean by ... 'the bulb has disappeared' ..?

Sometimes you can get a failure of the filament as a result of a jolt that gives you a dead short from the first filament support leg to the last. If that was the case it would be possible to get a high amp draw which would be enough to fry contacts. All this still leaves the question of why the switch was subjected to that load and fuses or relays didn't go instead.

Rather than hope everything is OK it would probably be a good idea to do some circuit and component checks both visually and with a multimeter. You can then have some confidence that you haven't got an underlying issue that ends up burning your pride and joy.

jeff spahn

I had that happen on the 82 Weissach I used to drive. Turned out to be a faulty switch. Replaced it and never looked back.

Mrmerlin

maybe your new switch didnt have a bulb in it
and thus the contacts shorted with some vibration..
Why did you replace the switch in the first place??
All of the bulbs are the same for the pod switches

I suggest to look at the CE panel for melted wires,

you may have gotten lucky and the smoke only left the switch...
but now is the time to check for melted wires on the back of the CE panel, disconnect the battery first.
Look for wires with a satin sheen instead of a dull finish,
satin indicates the wire saw lots of heat

Mark SF

I think the bulb fell out when I took the **** off to remove the switch. Which suggests that the bulb had worked it's way out and was lying loose in the ****.

I can see that the bulb contacts are now fused together and the switch plastic is melted around that point.

I checked the wiring to the switch, looks fine. I did feel the wires after the event and although hot they were not insanely hot. I think the damage is isolated to the switch. Also checked the relay and fuses.

I replaced the switch because the old one felt worn - no distinct click when going from one position to another. However it's back in use now and works fine!

I had all the switches out to fix the instrument lighting the other day, so I think that is when the bulb might have been left loose. I also remember having trouble pushing the little light bulb in at the time, so that may have been when the contacts got bent.