97urS6

Just purchased a 2002 Audi A6 4.2 Quattro, Ming Blue Pearl, Black interior. This was a very well cared for car, looks like it lived its life inside of a garage, it has every option that was available for that model year, including the solar sunroof... which is very rare in Canada. This will be my 3rd C5 A6 4.2 that I have owned, so I am quite familiar with them. However, it is having an unusual problem that I believe is associated with the headlight switch mechanism... here are the symptoms:
- headlight switch in the OFF position, the daytime run lights (ie. fog lights) are on as well as tail lights (as required in Canada)
- headlight switch in the parking light position, same as above, except the lights stay on when the car ignition is turned off.
- headlight switch in the ON position, the zenon headlights are on, as well as the tail lights
- headlight switch in the ON position + pulled out one stop, same as above, zenons on, tails on, but fog lights not on
- headlight switch in the ON position + pulled out two stops, same as above, zenons on, tails on, fogs off, rear fogs off

Also, some other interesting points: When headlight switch is ON, the headlight washer can not be activated. Also, when the headlight switch is ON, turn the engine off and open the driver door, there is no buzzer alarm that notifies you that the headlights were left on.

So with all of these symptoms, I think that the headlight switch has gone south, but because the headlights actually do come on.... I'm wondering if it could be something else?

Any ideas?

Harleyguy

I would think a full system scan with VAGCOM would answer your question, but possibly not. My inclination is the switch. Having said that it could be a relay or fuse also.Since neither fog circuits come on it could be either the switch or a relay. You will need to start tracing the circuit to see if the power is lost at the switch or elsewhere downstream. Do the headlight washer nozzles pop up and not spray? Separate pump for the headlights and it could be bad.

97urS6

Thanks for the quick response. I have run my VCDS Full Scan a couple of times and there was nothing that seemed to indicate that there was a problem. Actually, almost no codes at all... just a few that had good explanation and were easy to clear.

What I was going to try next, was to extract the headlight switch from my old 2003 A6 4.2, which its engine died (thus causing me to buy this one)... and try it in the Blue 4.2... see if that fixes the problem or points to something else.

Will keep you posted.

georgeb944

It will take you less time to swap the switches than it took to write your first post.

That is probably the issue.

97urS6

You're absolutely right about that... but I didn't think of that idea until I was about half way through writing the first post!!! LOL

Anyways, just back from swapping the switch... interesting results: the old cars working switch swapped over to the new car, did not fix the problem! Same symptoms!

I also did a reverse switch, and put the new cars switch into the old car.... and sure enough, everything still worked on the old car... so the switch is not the problem!

So now it is something else, does anyone know if there is a module or a relay that is in the path that might cause this type of issue?

georgeb944

I have attached a pdf of the HID headlights for the 2001 a6. Sorry I could not find any wiring diagram for your particular car, but they "should" be close.

There is a headlight relay (J123) probably marked with 393 on the top, in positions 9 and 10 (it's double wide) under the instrument cluster.
There is also a foglight relay (J5) in relay position 6. Cannot tell the markings from the picture...

Good luck, gb

georgeb944

Did some more searching and found the wiring for drl for canada. It might be more help... gb