Headlamps went off- then back on - Bad Switch?

[RussellK]

Last weekend I momentarily lost the lights. The headlamps went off, I reached down and barely touched the switch and they immediately came back on. It was suggested I replace both the light switch and ignition switch which I did. I questioned why the ignition switch and was advised the lamps are controlled through the ignition. Mine don't seem to be Regardless of ignition position my lights are on or off as controlled through the switch. If I look at the back of the fuse block all wiring looks correct. 3 and 4 fuses with black and yellow and yellow on one side and yellow on the other. I couldn't confirm the lights are controlled by the ignition in any VW literature I have so my question is twofold. Are the lights wired this way? If so where do I look next if the correct wires appear to be in the correct location at the fuse panel

[dtrumbo]

Are the lights wired this way?

Yes.

If so where do I look next if the correct wires appear to be in the correct location at the fuse panel

Right 'chere.


I've cropped out the irrelevant parts of the wiring diagram so you can more easily see what's what.
Starting at 'D', which is your ignition switch, note the black with yellow striped wire attached to terminal 'x'. This wire provides power to your light switch, 'E1' also on terminal 'x'. The light switch then provides power via the white with black striped wire to the dimmer relay (J) which then provides power to the fuse box via the yellow wire for low beams and the white wire for high beams. The yellow wire is one of the ones you noted in your original observation. You need to keep traveling "upstream" to see where things deviate from the diagram. Good luck and come back if you get stuck.

[Amskeptic]

Last weekend I momentarily lost the lights.

VW was proud to announce headlamps that only worked with the ignition on in 1971.
As dtrumboElectricalForumModerator pointed out, "X" is the power supply to the headlamps. Your symptoms do not suggest the ignition switch as a cause.
Disconnect battery.
Unscrew light switch knob and escutcheon.
Lower switch until you can get a visual.
Wiggle shaft where knob used to be.
Does plastic with wire terminals appear to be loose from the body of the switch?
You can try to snug things up by pressing tabs more firmly to hold plastic to body of switch. Follow up with small computer wire ties to hold everything together.
ColinDangIfIDidn'tDoThisJustYesterday

[RussellK]

I replaced the headlamp switch yesterday so I'm hopeful that fixes the loss of headlamps. As far as the switched / unswitched issue it looks like the next nice day I'll start tracing wires. Mine is incorrect somewhere. Thanks guys.

Added: Is it a problem the headlamps are working independently of the ignition?

[Amskeptic]

Added: Is it a problem the headlamps are working independently of the ignition?

No. Did someone put in an earlier switch? That will kill the kill-the-headlamps-when-you-kill-the-ignition "feature".
Colin

[RussellK]

No I went ahead and put in a correct new switch and the headlamps still work independently of the switch. I have a theory that I haven't tested yet that my aftermarket driving light may have something to do with this. I'm hoping to have some time this weekend to do a little tracking.

[Amskeptic]

No I went ahead and put in a correct new switch and the headlamps still work independently of the switch. I have a theory that I haven't tested yet that my aftermarket driving light may have something to do with this. I'm hoping to have some time this weekend to do a little tracking.

Since the headlamps get their juice from the dimmer, and the dimmer gets its juice from the X supply from the ignition switch,
IF
somebody made sure to power the aftermarket driving lights on high beam only AND/OR with its own power supply, you got an interesting sleuthing in front of you.
Colin

[RussellK]

First I eliminated the aftermarket lights as the culprit by removing the connection with the result being no changes to headlamp behavior. Then I set to tracking the headlamp wiring. What I found was the Black and Yellow ran from the X position on the switch to the back of the fuse panel. Lo and behold it runs right to the always hot position 9 (Door Warning Buzzer). It makes sense now why the ignition has no say in my headlamp behavior. Now what is the correct position? I don't know. I have no empty blades behind the fuses so wires must be plugged into the wrong blades. Maybe on purpose to have lights for late night campsite setups? Next I'll start looking at the ignition controlled positions back of the panel and see if I have something plugged in that should be always on.

[dtrumbo]

What I found was the Black and Yellow ran from the X position on the switch to the back of the fuse panel. Lo and behold it runs right to the always hot position 9 (Door Warning Buzzer).

The black & yellow wires on terminal 'x' of both the ignition switch and the headlight switch should be connected to the same side of fuse 10. Then when the ignition switch is on, power is supplied to the headlight switch and to whatever is on the other side of fuse 10 which would be the windshield wiper switch and the rear window defogger switch. Remember, fuses have two sides. The 'source' side (in this case the power from the ignition switch which then continues un-fused to the headlight switch) and the 'destination side' (in this case the wipers and defogger). Check where both yellow and black wires from both switches go and you'll find your answer.

[Amskeptic]

Edit Attempt

The Ignition Switch terminal 'x' supplies power to fuse 10 via a yellow/black wire.
Whenever the ignition is switched on, fused electricity is supplied to the wiper switch and the rear window defogger switch from the destination side of fuse 10.

The Ignition Switch terminal 'x' also supplies power to terminal "x" of the Headlight Switch via another yellow/black wire daisy-chained from the supply side terminal of fuse 10. Note that this power is fused individually to each headlamp further on down the ladder diagram as required by law.


(you know, technical writing is as difficult as any other writing, it took me a half an hour to try the above edit, and I don't even know if it is any more clear ...)
Colin