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Join Date: May 2001
Location: Northwest Florida
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Smoking Headlight Switch

I sure could use some help from you electrical gurus.

A few days back my headlight switch started smoking, out of the clear blue, and of course I quickly shut them off. The damage was done though, as the switch melted to the point that it couldn't be turned back on even if I wanted to. Anyway, when I finally got around to replacing the switch with a brand new one, you guessed it...switch #2 started smoking too. What would cause this? All my fuses look to be a-okay.
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Old 12-01-2002, 01:31 PM
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I wonder if the error lies in a wire in the dash near the switch and not the switch it's self.
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Old 12-01-2002, 04:25 PM
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Odd that your fuse didn't blow. Look in your owners manual, lights are segregated, i think, Hi and low, left and right have diff. fuses. Make sure they have the right amp fuse. It's just about got to be a grounded wire somewere. Start at the switch and work your way towards the light untill you find the culprit.
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Old 12-01-2002, 06:57 PM
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I would first check the amperage of the fuses you're running, then what type of headlights you have, etc. On 944s, all of the headlights' juice first goes through the switch.
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Old 12-01-2002, 08:26 PM
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generally speaking -- smoking wires are BAD. Your fuse would have to be huge to not blow before the smoking starts! This only happened to me one time and its because the wire was connected on the wrong side of the fuse and when it shorted -- Whammo -- a red-hot glowing wire that nearly started my VW bug on fire (wire was kicked lose but had started to melt stuff!). You have a serious short going on here.

I'm a mechanical engineer and OK with stuff I can see. I know enough about electricity to be mildly dangerous (rewired my garage w/ 220 and rewired the front of my new house); but, I would personally take it to someone who specialized in auto electric (get a recommendation though -- lots of igits out there). I have a fantastic guy here in Ft. Worth whos family has owned the auto electric bidness for years and can diagnos, and fix a problem faster and cheaper than I can -- and it's done right.
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Old 12-03-2002, 05:57 AM
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Thanks for the input, guys. I guess she'll be going to the shop...again.
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Old 12-03-2002, 06:54 AM
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Look for a short between the headlights or fog lights and the dasah lights.

I had this problem with my '84 after I "repaired" the fog light switch. I inadvertantly shorted the dash lights to the fog lights. In that situation the dimmer resistor was supplying current to the fog lights, melting the switch in the process.
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Old 12-19-2002, 05:18 AM
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Dimmer resistor...

It could very well be the dimming resistor is drawing too much current. That could cause some serious melty without blowing a fuse, maybe.

The fuse on that circuit could be 10Amps, the resistor rated at something pathetic like 1 Watt, and then the circuit giving it say 1A at 12 Volts for 12 Watts, or 12 times its rated power. Can you say melty?

This would be hard to track, as it could be one of your interior lamps is shorted/screwed in some way. Also, something could be drawing power through that dimmer that should not. I would unhook the dimmer and see if anything but the dash lights stopped working. If so, that could be your culprit.
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Old 12-19-2002, 06:12 AM
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The best thing to do at this point is go back over any electrical "repairs" that have been done recently.

Electrical problems can be a real PITA to track down, which is one reason I keep detailed records of ALL work that I do.
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Old 12-19-2002, 07:22 AM
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Still haven't taken it to the shop yet, so I appreciate the replies. I re-attached the switch to see if I could spot the source of the smoke...it was definitely coming from the dimmer. I haven't ever done any electrical fixes, so I'm guessing there's a rotted wire somewhere causing the short. This sucks.

As the switch is all one piece, how can I unhook the dimmer only?
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Last edited by dproshek; 12-19-2002 at 07:43 AM..
Old 12-19-2002, 07:41 AM
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Early 944 headlight switches are notorious for failing. Usually they melt internally and jam (always with the headlights raised!).
Replace the switch and inspect all the wiring and grounds. Make sure the the vehicle wire harness connector is good.
You should also make sure the current draw is correct and that the switch is not being overloaded.
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Old 12-19-2002, 07:54 AM
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If the plastic isn't melted too badly, disconnect the switch and insert a jewler's screw driver or similar tool into the hole for the dimmer terminal lug and release the latch. Once the latch is released, you can carefully pull the wire out of the connector.

If the plastic is toast, use a small pair of diagonal wire cutters or similar tool to nibble away at the plastic until the dimmer leads can be removed.
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Old 12-19-2002, 07:56 AM
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