Kirsten fog light switch shorts to dash

[70bus]

Hello, this may simply be a case of 'buyer beware,' but checking to make sure there isn't some other issue....

I have purchased two illuminated fog light switches for my 65 bus, one from a thesamba seller who listed it as made by Kirsten, the other off eby with no maker mentioned; however, aside from knob, it appears identical, if a little older.

The issue I am having is that when you pull the knob to activate the fog lights, the shaft, the escutcheon and any other metal parts are also connected to power - which immediately shorts the switch to the dash and blows the fuse. Needless to say, this makes them unusable on the bus. I have to assume that two having the same issue means that is as-designed and not a defect. What I can't figure out is what car these would be useful on, as for many decades cars had a metal dash, even if covered in plastic or rubber. Eventually that metal is going to contact an energized switch part...

In any case, take this as advice to look elsewhere than Kirsten for VW/Porsche fog light switches - are there other makes of illuminated switches that do not have hot parts when activated, or does the lighted knob mean they all are like this? I suppose I could drill the dash hole larger, install an insulating sleeve on threaded portion, replace the metal locking ring with a plastic one, etcetc but would rather not. For now there is a period toggle switch in dash.

PS - I want to make it clear that both sellers were not the problem; I am assuming 'tested/working' meant on the bench, and they had no idea there was an issue upon install. Both shipped quickly/packed well yadayada.
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Craig K
70 Neunsitzer
65 Pritschenwagen
"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams

Raul the 65 singlecab

Karl the 70 nine-seater

[Bub]

Is the connection you're testing the ONLY one that shorts to ground? Or do they all? Is it grounded at all times- or only when you pull the knob?
Looks like those have an indicator light in the knob- I'd assume that one pin will ground when the knob is pulled to ground the indicator light and turn it on.
I have seen switches that are intended for lights that have constant (or keyed) V+ to the light, and the switch grounds a relay or the light itself. Or some that were mounted in a plastic bracket so no ground to the housing.

There are a few ways to still use those switches, but maybe not the easy traditional way.
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[70bus]

From what I can tell with various wiring diagrams, the two 'on' tabs are for front and rear fog light circuits. It is possible they go to a relay first in some designs, but I don't see a way around the issue no matter what the scheme.

When knob is in, all metal parts - including the paired tabs obviously - are dead. Pull the knob and ALL metal parts go hot.

I think the issue is that I was expecting these switches to be like other illuminated switches on a VW (e.g. emergency lights) in that the shaft is insulated from the rest of the body in some way: a sleeve, or rubber rings. These clearly are not. If the dash is totally plastic, or you have it in a non-conductive below-dash mount, it isn't an issue. I was hoping to mount these in an existing hole in a metal dash, but short of enlarging that hole to put an insulator of some kind in, I'll have to keep looking.

Before I spend more money - switch and fog light experts, are there any suggested illuminated switches that do not behave like this? They would need to be small in size like these to fit the dash space, and hole between 10 and 12mm (current hole is 10).

I have the fogs set on a keyed circuit, so I won't leave them on accidentally with the toggle and drain battery... but lighted knobs are more fun if I can find the right one.
_________________
Craig K
70 Neunsitzer
65 Pritschenwagen
"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams

Raul the 65 singlecab

Karl the 70 nine-seater

[70bus]

I dug out my 66-only bus emergency switch, which also has a lighted knob; as this goes into a solid metal dash I thought things would be different. Nope! Pull the knob and all metal parts are hot.

I do not know the current flow through the 9-pin box the switch goes, so I can't tell ifthe switch gets power through it, or completes a ground but it sure looks like it completes a hot circuit - the bulb is shown apparently getting power through K and then grounding at dash.

Obviously the load (bulbs, etc) means this isn't simply a dead short to ground, and the fuse shouldn't blow... but it does. Everything is cool when tested but put it in dash and -pop-

What am I missing on these switches? Whether the switch connects a hot lead or completes a ground circuit, 12v is gonna hit the dash through the metal body parts and that pops a fuse.


Note the this T3 circuit does not have a lighted switch; I assume an illuminated one here would bow the fuse.

This is a differnt switch, plastic-bodied I believe... and doesn't appear to ground through body. The actual light circuit is what i expect mine are: input (83) and front and rear output (83a 83b) so i don't think I have a wiring layout issue. This one is too big for my space, tho.

I am running LED fog bulbs, so i don't need a relay to trigger power to them and it can just go through any switch capable of handling a few amps. I am happy to try any other wiring scheme if that makes this work!
_________________
Craig K
70 Neunsitzer
65 Pritschenwagen
"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams

Raul the 65 singlecab

Karl the 70 nine-seater

[70bus]

I found another switch, and it actually has the illuminated shaft insulated from the rest of the switch.

The last pic showed the shaft connected to ground and the unshown multimeter which indicated no current.

So I hooked the first one up based on how the new one was wired (hot too 54. Light to L, Ground to K on this; on the first switch, hot to + , light to S and 31 to ground as usual) , and amazingly it seems the shaft is now no longer live. So I need to slap it back in the truck and see if it really doesn’t pop the fuse.

Weird bulb size; the seller couldn’t find a match. Teeny, and like a flashlight bulb. Anyone know what type I’m looking for?

For MORE fun, the switch at top with black knob has terminal designations of 31, S and K. When power is connected to S And K is connected to bulb input (bulb housing is grounded), pulling the switch results in light on, but switch knob not lighting. Connect 31 to ground, and the bulb is lit and light goes on… but the switch and knob shaft are hot and will blow fuse if in a metal dash.

Power to K and bulb ground to S lights knob but NOT bulb. At least the shaft isn’t hot! Power to S and bulb to K lights bulb weakly and knob glows dimly; shaft hot. Connecting 31 to ground with this circuit is a dead short. Connecting any iteration of hot and ground to 31 and K is the same except grounding S does nothing.

Confused? Moral of the story is that identical-looking switches may not work the same electrically. I got lucky in that one of the switches hopefully provided the clue to get one to work the way I need it to for the fog lights
_________________
Craig K
70 Neunsitzer
65 Pritschenwagen
"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams

Raul the 65 singlecab

Karl the 70 nine-seater

[70bus]

Just a belated update: one of the sellers provided a sketch of how these switches are wired

Howverer, the issue of all metal parts being live when knob is pulled is still there. So still looking for a lighted fog switch that won't blow fuses!
_________________
Craig K
70 Neunsitzer
65 Pritschenwagen
"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams

Raul the 65 singlecab

Karl the 70 nine-seater

[70bus]

A bit of a further update: I was playing around with these switches again, and the one pictured just above, with the big green toggle, does not short to dash, as the toggle shaft is in a plastic insulator (you can see the black plastic inside the knurled trim ring). However, neither it, NOR a similar one that has on-off-on functions will light. The bulb they are connected to does, but the bulb in the toggle does not... unless you force the toggle a bit farther. Apparently they are poorly manufactured and the internal contacts do not, well, contact! When you force the toggle over to get it to light, the bulb they are switching goes out. Just to add insult to injury.

Moral: avoid all these repro fog light switches (the 2 position one says "Malta" on back) as they are difficult to find bulbs that fit in them and are garbage internally.
_________________
Craig K
70 Neunsitzer
65 Pritschenwagen
"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams

Raul the 65 singlecab

Karl the 70 nine-seater

[Frederik]

I saw you got another switch, but you got the answer from Bub. The switches that "shorts" to chassie is intended to use to switch on/off the negative/- signal to a relay. Why? Well you didn't have to run a + wire from whatever you wanted to the fogs to turn on and off together with (according to regulations) and back to a relay (not so much a problem in a bus) You could just use chassie - where the switch is as "switched" signal to 85 on relay.

This is an example of wiring (even if its an non illuminated switch) where they only are able to turn on with low beams:

So even if you don't feel you need a relay with the LED bulbs, you could still use the switch if you do. There are some ways to wire this depending on how you like it to work.

If you want them to turn on (switch on) independent of other lights, but turn of automatically when ignition is off

- From switch to relay 85
+ From ignition 15 (from fuse box) to relay 86
+ Supply (fused) from battery/30 to relay 30
+ Feed to fogs from relay 87

[70bus]

Thanks Frederik; I went through a number of your gallery pics and posts about fog lights! What I have learned is that any lighted switch tends to get called a 'fog light' switch, but the actual terminal numbers will tell you what it might have been for and how to wire it. i agree some of the ones I have must have been designed to ground a circuit, but I haven't tested them all for that. I found one that worked as I intended and left it at that. I was trying to avoid using a relay and cluttering up the area under dash or behind kick panels, so a switch that grounded a relay was not useful.

I've also had an interesting discussion with NA Skeet on fog lamps, US vs. Euro and UK regulations, and wiring mods, so it was a useful effort.
_________________
Craig K
70 Neunsitzer
65 Pritschenwagen
"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams

Raul the 65 singlecab

Karl the 70 nine-seater