Headlights not working properly?

[Canada Kev]

OK, I'm not completely positive there is a problem here, but in my experience with other vehicles, I think there is.

When I pull the head light switch to the first notch, I expect only the running/parking lights to come on. The second notch should turn on the head lights. Is this the way it is supposed to work for a euro car?

Currently my head lights come on at the first notch. And stay on at the second. Both notches are operationally the same.

So, its a buggered light switch, right? Well, not so fast. When I put in a new switch, moving the connected wires one at a time so I don't get them mixed up, it works exactly the same way. So now what?

I don't think it is likely that something was moved about over the years because the car is just so unmolested, but you never know.

So, after all that, does any one know what each connector on the switch is for? There is quite the collection and the Bentley manual is woefully inadequate.

And question two: is this normal operation for a euro car?

And the obligatory pic:




Pin numbers starting at just before 12:00 are as follows in a clockwise manner.

58
30 - two pins in parellel
58a
57
75 - two pins in parellel
58R
58L
N
56

[Canada Kev]

OK, I suppose in my frustration I was mistaken in saying Bentley's diagram was not useful. I was kinda wrong.

This is what I have gathered. Perhaps someone can pipe up and tell me if I'm on the right track. i suppose it would help if I had a pic of the actual wires on it switch in my dash. Maybe a bit later. Like tomorrow. Anyway..

30 is my 12v power.
N is what? a ground point?
57 speedo indicator?
58L left light
58R right light
58 interior lights? I don't know how these would be in the ckt
58a don't know
75 don't know
55 don't know

I pulled out my continuity tester and this is what I found:

At the first notch I have continuity between 30 (power in) and:
-58
-58L
-58R
-58a
-57

When out at second stop, pin 57 loses continuity with 30. All other remain the same.

I also found continuity between pin 75 and N on both active positions.

So from what I can gather here, my lights will be on whenever the switch is on either of the active positions. Is this proper? Is my switch buggered?

[Canada Kev]

OK, I just checked a third old switch I had in the basement. It is the same in that if there is power to pin 30 the same pins get power at either of the two powered switch positions.

Is this the way the lights work? Head lights on both positions? I don't see anything that suggests otherwise in the wiring diagram.

I don't quite understand where all this power is going. I don't think my signal switch is acting up. Normal functions like signalling and hi/lo beam work as expected. And the way these diagrams flow is a bit odd to me. So far I'm stumped.

[Hugh R]

Moral support only here. Wish I could offer more. The best thing I did was take the wiring diagram and enlarge it a lot. I had the turn signal, high low switch go out and I replaced it and I actually had my headlights dimming with the dash light dimmer! Turns out I had connected a wire that is "extra" on the new stalk switch to an available terminal on the wiring harness. I feel for you.

[Daviboy]

Kevin,
Dont know if this helps but I recently had an issue with my 82sc headlights and posted this thread Fog Light Relay Question in the hope of someone helping out. Turns out I solved it myself. Oh and BTW on the first pull my headlights come on like very low beam and second pull is normal, when trun stalk pulled they flash high beam and pull high beam on permanently.

[Canada Kev]

Daviboy, your 'very low beam' is likely your city lights. i am assuming all ROW cars have these, though I may be incorrect.

This evening or tomorrow will be a bit of trouble shooting on the car with a test light or meter to see exactly when there is power from the switch and from where. I still don't understand why all those pins have continuity to the power input at BOTH first and second notches. They are almost identical. How does the system know if you are on just parks or head lights?

[Mysterytrain]

Kevin,
Some questions. Is this car new to you or is this something that has just popped up?
Did someone install headlight relays? Has the turn signal switch been replaced recently?

[Mysterytrain]

Looking at the SC schematic:
Power comes into the switch at two terminals, 30 and 75
Terminal 30 hot at all times
Terminal 75 Hot in on/run.
Terminal 56 is the feed for the headlight circuit only
Terminal 57 is the parking light indicator.
Terminal N [ which I assume is K on the factory schematic] is for the license plate lights & the non-fused ashtray light
Terminals 58L and 58R are for the left and right parking lights
Terminals 58A are the interior lights

[Mysterytrain]

Additionally:
The headlights should only be on if the key is in the on/run position. That is the only time power is supplied to terminal 56. This explains why when you turn the car off at night the parking lights remain on but the headlights turn off.
Terminal 30 should have 2 wires attached to it a red wire and a Red/white wire. The red/white wire goes to the headlight flasher switch so you can flash your lights at boxsters, but they won't flash back.
There are two green/blk wires on terminal 58L and two green/red wires on Terminal 58R
Only one White/blk wire on terminal 56
A red/white wire on terminal 75
Green wire and a blk/blue wire on N
White green on 57
3 black/blue wires on 58a
I'm not sure what happens if those red/white wires are mixed up. They should be easy to test as to which is which. Remove the Red/white wire from Terminal 30. Put a meter on it and it should have no power even with the key turned to on/run.

[Canada Kev]

Originally Posted by Mysterytrain

Kevin,
Some questions. Is this car new to you or is this something that has just popped up?
Did someone install headlight relays? Has the turn signal switch been replaced recently?

Yes, this car is new to me. The problem has been there since I have owned the car. I didn't worry about it as I thought it was just a bum switch. I got the new one and issue still exists, thus this post.

I installed head light relays. This is a thing I do with most vehicles I own. At least those that don't have any originally. I am a believer in good lighting and since these 911s have kind of a mickey mouse lighting thing goin on, it was a no brainer for me.

I do not know if the turn signal switch has been replaced. I suspect not.

[Canada Kev]

The short answer is yes, they were working correctly, just wired INcorrectly.

Let me explain: After breaking out the test light just to determine which pins actually had power at different key and switch positions, I managed to come up with a matrix of what's what. Or what should be what.





So, according to my little drawing and Mysterytrain's helpful information (thanks), I concluded that the wires connected to pin 56 should be my lights. So I unplugged them. Lights stayed on. Which ones stopped working? My license plate lights. So I start thinking, which is incredibly uncomfortable on the weekend, and after labelling, unplug the wires on pin N which is for the license lights. Well, what do you know, the head lights go out. Swap the wires over on both accounts and check. Everything works. Cool.

So I button it all back together and then check again. All works well, but I don't like the action of my new switch which was still installed. So I take it all apart again to put in the old switch and keep the other for a spare. Test the lights and headlights don't work. QQF? Break out the test light again and no juice on pin 56. At this point, I am pretty proficient at R & R the head light switch, so 25 seconds later, my new one is back in and operating properly.

What I think happened is that in the past, someone experienced headlight failure as a result of a bad switch. Seeing that all other functions of the switch were working fine, and the person didn't want to shell out a bunch of cash for a new switch, the "fixer" just swapped positions of the HLs with the license lights.

Now it works the way it was originally intended and I have a couple spares: one that kinda works in a pinch and another that is unknown.

Thanks to Mysterytrain's help the in identifying the switch pins and their function.

[Canada Kev]

I just noticed that on the matrix I have pin 57 (dashboard parking light indicator) showing voltage with the ignition on with the switch at the first position. This is INCORRECT. It should be in the next spot with ignition off and switch in position 2 and should be swapped. That pin is only powered with the ignition OFF and the switch in any ON position. Sorry for any confusion.

[Mysterytrain]

Cool Kevin, glad it worked out

[pete3799]

I just noticed last night that my headlights do the same thing : on in first position.
Don't know if this helps or not mines a RoW also.

[Canada Kev]

Mine didn't do it because it's an ROW car. It was because someone in a past life figured it would be an idea to hook up the head light wires to the license plate light lead on the switch. The license plate lights were on the wrong lead as well, I believe.

Your best thing to do is likely to just pull the switch (easy to do), check if there is power at each lead when its supposed to be there to get a baseline, and then if necessary move the connectors to where they should be. A tip that I would follow is that if you disconnect any wires, LABEL THEM. Get some tape and a sharpie and number the position it was in before you took it off. You could use the pin number (30, 58, 75, etc) or do like I did and just number them 1 - 9 in a clockwise direction using pin 30 (power in, hot at all times) as position #1). The numbers for the pins can be difficult to read.

After I did the matrix of how the switch worked, it was easy to see which pin each light should be connected to. If the pin only gets power with the key on and with the switch in the outer position, it will be for the head lights.

Good luck, and if you have any difficulties, ask away. I feel pretty confident I have a handle on how the light switch works, now.