Help, Headlights won't turn off! SOLVED!

[Matty-MK3]

Check all wiring plugs for burning/melting?

[Mars Attacks]

Now then, just a little update and a request for help again for advice

i borrowed a multimeter from a guy at work and have had a look at the car again over lunch,

as expected on both head lamp clusters there is a constant 12.5v live feed present which would explain why the lights are permanently on. i tried following the cable round on both sides of the engine bay till they dissapeared but could see no signs of frayed cable or loose connections.

back inside the car, i took the headlight switch out and with the switch still plugged in i identified pin 11 (red and yellow cable) as being live at 12.5v while the rest appeared to be dead. I unplugged the switch and checked again and the pin 11 remained live. From looking at one of the guides on here, it looks like pin 11 is supposed to be live anyway so that doesn't help.

i tried pulling the fuses for headlamp left and right and they do go off as they should do.

i'm no auto electrician by any means so if anyone could draw any conclusions from any of that i'd be very grateful. if you need any more info let me know. thanks again.

[AudiA8Quattro]

Thinking what i posted before, i don't think there should be constant live feed, until the switch is turned on.
If you unplug the connector from the light switch, do you still get a live feed at the lights?

[Mars Attacks]

hi, yeah i've just been out again and tested that and the lights do remain on when the switch is disconnected.

one strange thing i have noticed although it will have been like this for the 2 years we've had the car, but on the plug that goes into the headlamp cluster, on both sets of headlights, 2 of the wires look like they have been cut close to the plug and then reattached as they each have identical wrappings of electrical tape.

I wondered if this could be a sign that the headlights had been uprated and bring us back to the stuck inline relay problem? i did have a look and couldn't find one but it might be there and i just haven't spotted it??

clutching at straws i think!

[javalin]

very interesting.

I would expect the power to the lights to be off when the switch is off - i.e. the live is switched.

So something is powering the lights after the fuse but other than the switch...  Have you a Haynes/Bentley's manual?  Else I'll look in mine tonight and see whats on the circuit after the fuse & switch.

What mk3 is it?  GTI?

James

[Mars Attacks]

Hi i don't have a haynes manual for this car. its a 95 gti 8v if that helps.

i'm guessing it must be earthing somewhere incorrectly but nothing looks out of place when i look around the wiring. any help would be great thanks.

[FlySpeck]

there is no relay normally, and as said, the switch gets the live first, then it splits to the 2 fused feeds to each light as far as I remember, so somehow those fuses are getting a 12v feed by some problem at the fuse box maybe. Also, theres a feed to the stereo from the lighting circuit to tell it to dim the display, if that got shorted to the 12v feed next in the plug that powers the stereo, that would back-feed the sidelight circuit, and may even put on the main beams depending on earthing arrangements.

WHat you can try, is pulling every fuse one by one EXCEPT the 2 dip beam ones (1 & 2) and see if killing anything else, kills the phantom lights - and there may be your culprit.

I'll try and dig out the lighting circuit and see how its wired, I have it somewhere.

[Mars Attacks]

thats a good idea pulling the fuses, might lead me to the answer, will have a try tonight. thanks for the info.

[javalin]

Hiya

Looked at the diagrams for these circuits in Haynes and Bentleys - and apart from not being able to find the on/off switch (so lights should always be on! lol) the only other obvious cuprit is the the indicator stalk - but that would be main beam.  Hmmm.

Are you sure that the headlight switch does power off - i.e. not stuck on?

James

[Mars Attacks]

evening, well i've tried some more stuff and still getting nowhere.

the indicator stalk still works fine when pulled back as the full beam lights turn on and off so its not that like you say,

with the light clusters plugged back in (so the headlamps are annoyingly on! ) i pulled out every fuse one by one apart from 1 + 2, but the lights stayed on so i can eliminate that. i also removed the stereo and checked for any loose wiring back there and nothing, all neat and tidy.

i've been round the engine bay from the right headlight, followed the wires across the slam panel, through some strange circular multi plug, into the left headlight and back under the airbox and out of sight towards the fuse box. all cables are still wrapped up and no sign of frayed edges or loose wires.

the headlights stay on with the headlight switch unplugged completely so i thought that eliminated the switch as a problem?

i'm looking at some weird earthing problem or something i can't see in or behind the fuse box. i can't understand how it went from being fine at about 8pm on sunday, then driving hoke for 15 miles and then the lights sticking on. Been trying to think if anything happened on the trip home that might have triggered it, but i can't think of anything. i did have a passenger so is it possible there is something in the passenger footwell that could have been kicked or damaged. clutching at straws again.