New headlight switch smoking

[CharlesJones]

Hi all,

I have just replaced my headlight pull switch, which had been becoming increasingly unreliable over the last few months. The old switch at first lost the "feel" between the first pull stop (for side lights) and full pull, and then started to need a bit of twisting and fiddling to get the lights to come on, before not working at all. So I bought a new switch (cost a lot!) and swapped the switch over taking great care to put the wires on the same terminals of the new switch as they were on the old.

I tested the new switch whilst it was still dangling under the dash board, but it did some odd things. I found at half pull I got the fog lights along with the side lights, and then at full pull I got the headlights fine, and the rear fog light went out (front fogs stayed on). And then there was something odd going on with the illuminated switches on the dashboard too (the window demister switch, fog light switch etc) - at half pull they illuminated whereas at full pull they didn't - something like that anyway. Any how, then my expensive new switch then started smoking! It looks like solder or something is oozing out between the wire wrappings from inside the switch, so I hastly disconnected the battery. I don't know if the switch would have smoked in the off position, or only in the on - I didn't want to risk destroying the new switch in trying to find out!

Do any of you know what might cause the switch to smoke? I don't think the new switch is faulty - its a genuine porsche part, and looking at the old switch it looks like a section of those wire wrappings has burnt out, which might be the reason the switch stopped working. I am not great with electrics - I am learning, and possess a multimeter and know about basic stuff like voltage drop testing, but that's about the extent of my knowledge at the moment (I want to learn though!).

Also, do you think if I fit a headlight relay kit it might help this problem? I want to fix the problem properly of course, as opposed to just mask it, but I was thinking that presumably fitting a relay kit would involve some new wiring which might irradicate a possible short. And at least with relays I wouldn't be risking my expensive new headlight switch!

Many thanks for your help - any advise is greatly appreciated!

[DRACO A5OG]

I ordered a switch from the dealer OEM but the part was obviously defective, it had a dead spot on pull. I had to replace with a good one.

[86 911 Targa]

Originally Posted by CharlesJones

Hi all,

I have just replaced my headlight pull switch, which had been becoming increasingly unreliable over the last few months. The old switch at first lost the "feel" between the first pull stop (for side lights) and full pull, and then started to need a bit of twisting and fiddling to get the lights to come on, before not working at all. So I bought a new switch (cost a lot!) and swapped the switch over taking great care to put the wires on the same terminals of the new switch as they were on the old.

I tested the new switch whilst it was still dangling under the dash board, but it did some odd things. I found at half pull I got the fog lights along with the side lights, and then at full pull I got the headlights fine, and the rear fog light went out (front fogs stayed on). And then there was something odd going on with the illuminated switches on the dashboard too (the window demister switch, fog light switch etc) - at half pull they illuminated whereas at full pull they didn't - something like that anyway. Any how, then my expensive new switch then started smoking! It looks like solder or something is oozing out between the wire wrappings from inside the switch, so I hastly disconnected the battery. I don't know if the switch would have smoked in the off position, or only in the on - I didn't want to risk destroying the new switch in trying to find out!

Do any of you know what might cause the switch to smoke? I don't think the new switch is faulty - its a genuine porsche part, and looking at the old switch it looks like a section of those wire wrappings has burnt out, which might be the reason the switch stopped working. I am not great with electrics - I am learning, and possess a multimeter and know about basic stuff like voltage drop testing, but that's about the extent of my knowledge at the moment (I want to learn though!).

Also, do you think if I fit a headlight relay kit it might help this problem? I want to fix the problem properly of course, as opposed to just mask it, but I was thinking that presumably fitting a relay kit would involve some new wiring which might irradicate a possible short. And at least with relays I wouldn't be risking my expensive new headlight switch!

Many thanks for your help - any advise is greatly appreciated!

Charles,

Let's start at the beginning:

When I replaced the headlight switch in our '86, I disconnected the battery, and documented the connections.

Please compare this to your wiring:



And here are the color codes:

SW-BLACK

WS-WHITE

RT-RED

GN-GREEN

GE-YELLOW

GR-GREY

BR-BROWN

BL-BLUE

U-VIOLET



pm me as needed.

Good luck,

Gerry

[CharlesJones]

Originally Posted by DRACO A5OG

I ordered a switch from the dealer OEM but the part was obviously defective, it had a dead spot on pull. I had to replace with a good one.

Thanks - so I shouldn't be too trusting of the new switch if all the wiring turns out to be correct.

And Gerry, thanks VERY much for your post! That is a wealth of information. I had searched the forums for information like that which you gave me, but the only thing I could find was hard-to-follow wiring diagrams. Your much simpler labelling and colour coding list of the wires is so much more helpful!

What I will do is double check the wiring as per your post tomorrow night. It might be that the old switch was wired incorrectly, or maybe that I got the terminals mixed up when I transferred the wires over. I will report back what I find.

Thanks again Gerry.

[JJ 911SC]

Gerry

Thanks for sharing Help yourself to a beer or two

JJ

[CharlesJones]

Hi there,

My apologies for not updating this thread sooner. Life has been somewhat unpredictable recently, and I have only had opportunity to go and look at the car today! Very frustrating!

I've examined the wires into the ignition switch as best I can, and compared them to the diagram which Gerry very kindly posted above. Its a little difficult since some of the wires are a a bit cruddy so its difficult to tell exactly what colour they are! However, I think they all go to right places with one question mark. There is a big yellow wire which goes from pin 56 (high/low beam flashing) to a connector which has connects it to a blue/black wire which loops back and connects to pin 58a (instrument lights). Therefore 58a actually has 3 wires going into it - I think 2 of these are blue/black and one black - where as 56 has 2 wires going to it - a white/black one and the yellow one as described. Does this sound okay?

Also, it suddenly occurred to me that I have been testing this switch whilst it has been dangling in free air under the dash (i.e. not fitted). I see that when actually fitted it has a metal washer which faces onto the metal face inside the dash. Does the switch need this for the earth? Could that be why it has been smoking?

Many thanks again for your help.

Best regards,
Charles.

[CharlesJones]

Hi,

I have another update. I have just tried attaching an earth to the switch and that helps. I still get some weird behaviour, but the switch no longer smokes when I have the ignition on.

Low beam and high beam work fine. However, the front fog lights are on for both high beam and low beam (makes no difference what the fog light switch is set to), and the rear fog light comes on for low beam but not high (again, regardless of what the fog light switch is set to). Also, I can hear a fan come on under the dash board on the passenger side when I have the headlights switched to low beam. I don't know what that fan is - it goes off if I turn onto high beam, and also if I turn the headlights off, but is on for low beam.

More worrying though is that the headlight switch still smokes if I have the ignition turned off and the headlights or sidelights turned on. Do any of you know why that might be? I still have the earth in place - the switch just starts to smoke with the ignition switch off and headlights on.

Thanks for your help. Any advice/suggestions greatly appreciated!

All the best,
Charles.

[CharlesJones]

Hi again,

I just wanted to update this thread in case it is of help to anyone else who has a similar issue.

Well I still haven't fixed the problem conclusively and completely, although I have significantly alleviated the problem. I decided it would be best to fit a headlight relay kit, since I had heard it takes the high current off the headlight switch and the dip/high beam steering column stalk. I was thinking that might stop my new switch from burning out, and would allow me to investigate the issue without wrecking my new expensive switch.

The relay kit I fitted was the one by J West Engineering, and is sold by Pelican. At 25 USD I think its fantastic value - in fact, I wonder how they manage to sell it at that price. The kit comes fully assembled and with comprehensive instructions. All you do is join a couple of wires, screw it under the fusebox (using existing factory screw) and connect it to the battery. I think it took me about half an hour to fit, and now its in place I don't think anyone would guess its not factory.

Anyway, after fitting the kit my switch no longer smokes and burns - in fact it hardly gets hot at all. The relay kit completely eradicates that problem.

I still get some weird behaviour with the electrics - whatever problem I have with the wiring hasn't been fixed by the relay kit of course, although the problem does seem simpler now. The front fogs come on with the headlights, but the rear fog light won't come on at all, and I can hear some sort of fan start-up under the dash board when the headlights are turned to dipped beam, but the fan stops when they are turned to high beam. However, these problems aren't critical so at least I can use the car now. And the fact my headlight switch doesn't smoke anymore means I can investigate these problems at my leisure without risking the destruction of my new 200 euro switch! I strongly recommend that anyone fits one of these relay kits - even if you electrics are fine. At the price they are, and the fact they are so easy to fit, it really is worth the cost and effort as a pre-emptive measure against any future problems.

My thanks again to Gerry for that diagram and hugely helpful post which he posted.

All the best.

[dshepp806]

Not sure you're quite yet out of the woods.....do keep an eye on that "smoke" issue....and ID exactly where it's (was) coming from.

The relay kit definately helps with minimizing current flow THRU the stalk switch, for sure. Not quite sure of the correlation to the headlamp switch (as to the mod, as I see none-that is it carries what it carries there).

Time to trace some wiring, eh?

Doyle

[CharlesJones]

Thanks for the advice Doyle. The switch was smoking pretty badly, and just after a few seconds of having the headlights switched on with the ignition key switched off. It was difficult to see exactly where the smoke was coming from, but the coils of wire inside the casing of the switch had started to melt - I could see that through the gaps in the switch casing. It was difficult to experiment or investigate the smoke issue since I was worried about the damage to my new switch! Everytime it started smoking I would just panic and pull the battery cable as soon as I could.

I thought the relay kit would mean that power to the headlights would now not be routed through the steering column switch nor the headlight switch anymore. Certainly after fitting the kit I couldn't get the switch to smoke again, although I completely accept the possibility that might be because of some other reason.

Yes, it looks like I will need to get dirty with the wiring like you suggest. I just wish it was all a bit more accessible in there - it looks a bit tight under the dash! It will be a good learning experience for me though, and I would like everything operating as it should be with no risk of that recurring smoking switch of course!

[hcoles]

If the quality of the switches is going down adding a relay system could be a solution. One would assume that if components got hot enough to smoke, even if the root cause is fixed, the switch is now likely not in great shape.

Regarding the loss of smoke, I had to add this.

[CharlesJones]

ARGH!!! My electrical woes continue! I took the car out for a spin today - the first time at night since fitting the relay kit and replacing the switch - and what I found is that the headlights work fine, and in fact seem brighter than they used to be prior to fitting the relay kit. However, when I put the headlights onto high beam the instrument lights go out! Switch back to low beam and they come back on again - its just whenever I go to high beam that they go out. Its the dial lights I mean - the speedo, rev counter, fuel guage etc.

One thing I found was that if I have the headlights on low beam and then gently push the stalk towards high beam, without actually making it click into highbeam position, then I can get the headlights to go to high beam with the instrument lights still illuminated. But then as soon as the stalk clicks into high beam position the instrument lights go off again!

Can anyone suggest any reason why this might be happening?

Many thanks!

[Quicksilver]

Don't have an answer for you but have an additional cautionary mod for you and a general design note to keep in mind.

- First, I'd recommend that you do the dash wiring fuse mod. (search the forum for info) A bunch of the under dash stuff is unfused. Wiring is one thing Porsche didn't have a handle on...

- Second, keep in mind that the location of the fuses in the wiring circuit is just plain silly. Instead of putting the fuses as close to the battery as possible Porsche has put the fuses in the middle of the circuits. The power comes from the battery, to the switches in the dash, then to the fuses, and finally to the load/device. It just begs for a wiring fire.

[JJ 911SC]

They are more mechanical woes... associated with the stalk.

If memory serve me right, DRACO A5OG got a good thread on this.

[86 911 Targa]

Originally Posted by CharlesJones

ARGH!!! My electrical woes continue! I took the car out for a spin today - the first time at night since fitting the relay kit and replacing the switch - and what I found is that the headlights work fine, and in fact seem brighter than they used to be prior to fitting the relay kit. However, when I put the headlights onto high beam the instrument lights go out! Switch back to low beam and they come back on again - its just whenever I go to high beam that they go out. Its the dial lights I mean - the speedo, rev counter, fuel guage etc.

One thing I found was that if I have the headlights on low beam and then gently push the stalk towards high beam, without actually making it click into highbeam position, then I can get the headlights to go to high beam with the instrument lights still illuminated. But then as soon as the stalk clicks into high beam position the instrument lights go off again!

Can anyone suggest any reason why this might be happening?

Many thanks!

If you have the JWest relays, please verify wiring as per my installation.









Good luck,

Gerry

[86 911 Targa]

And here is the 3A dash fusing proceedure:

[86 911 Targa]

[CharlesJones]

Hi,

Thanks for all the suggestions again, and thanks very much for the photos and diagrams again Gerry. That inline fuse looks easy enough to fit, so I will see if I can pick one of those up from my motor factors tomorrow - I presume they sell them ready made. I will then double check the installation of the relays, before attacking the headlight switch with a multimeter to see if anything is affected by the operation of the column switch somehow. I found when previously checking all the connections at the back of the switch that there is is a big yellow wire going from pin 56 (high/low beam flashing) to a connector which connects it to a blue/black wire which loops back and connects to pin 58a (instrument lights). I am not sure what pin 56 actually does (its labelled "high/low beam flashing") but the fact that a wire loops from it back to the instrument light pin makes me wonder if it has something to do with the problem.

As far as I can see the only light on the instrument panel which should be affected by the operation of the high/low beam column stalk, is that blue light on the speedo which indicates high beam. I can't see that blue light on the wiring diagram which Gerry has provided above, but I am wondering if that is associated with the problem. This blue light does work okay though - it illuminates for high beam, even though the other dial lights all go off.

I will report back what I find. Thanks again for all your input.

[airbil]

CJ
I feel your pain. In fact I parked the car for 16 mos due to electrical frustration (and smoke) post new headlight switch install.
I snapped out of it just a couple mos ago determined to find the problem.
Yes, I had one wire incorrect. Voila'!
So that fixed that, but still I kept blowing fuse circuit 18.
Issue was the wire that had melted and I had to run new wire for that circuit... Clock, glovebox, hood light and interior lights. Lucked out cuz that wasan ez circuit.
But; there's a lot of wires within the harnesses and if one melted, there could be short circuit trouble.
Long story short, triple check the headlight wiring. Hopefully you find something there.
If not, LOOK carefully for melted / burned / bare wire/s. Follow all melted wires into their respective harness until they appear to be good (not melted). Cut off and replace any melted wire/s.
Not fun but these are very old harnesses.
Butofcourse it may also be a good idea to install another new switch.
Good luck !
Report back.

[Hugh R]

IIRC, there is a wire you aren't supposed to connect to the switch. I know that sounds stupid, but about 8 years ago, I replaced my headlight switch and when I turned the dash dimmer up and down the headlights went bright to dim. I "think" it was a yellow wire, but couldn't be sure. Sorry not much help.