Both headlights not working - please help

OK - I'm new to all this but hoping you can help.

The dipped headlights on both sides of my A2 have stopped working. My indicators, main beam and side lights are all fine. At first I assumed I was just really unlucky and replaced both headlight bulbs but this hasn't helped. I've had a look at the fuses and reckon they are OK (I swapped them around with the one in the rear fog light and it kept working). I've also popped out the headlight switch and had a look at the back and all the wires are firmly in place and I can't see any burnt wires or anything obviously wrong.

My neighbour helped a bit and we measured the voltage at the bulb but there's nothing there. Does anyone have any idea what to look at next? It would help if I understood where the wires go after the switch? Also, are the right and left headlights completely seperate all the way from the switch or is there a common part and then a point where the power splits?

Thank you

I don't know for sure and am guessing, but could they both be on a relay that has failed? Could be worth looking at the relays too. Can't help much more than that I'm afraid, but I am sure someone "in the know" will be along soon to be of more help..
Thanks Lee. That was kind of the conclusion my neighbour and I came to. Only problem is we're not sure where the relays are? Any ideas?

Hi chubbybrown.

I'd kind of ruled the switch out because I do get sidelights and the light on my dashboard indicating the lights are on. So, the switch is partially working. Do you think it's possible for part of it to fail? I'm not quite sure how to test it really. Any thoughts?

I have however located the relay thanks to the following thread which I found late last night.

I had to remove the plastic panel under the steering wheel and there were two relays. Relay 9 is grey with a big 370 on the front (part no: 8D0 951 253) and there are quite a few on ebay for about £6 so I think it's worth getting one and seeing what happens.

Luckily, I'm far enough north that as long as I'm not out too late I won't need headlights for a bit.

Thought I'd post an update as I've reached a diagnosis. Earlier attempts were a bit scatty as kids kept interrupting.

From the other thread I found the dipped beam circuit goes like this:

Battery - ignition switch - relay 9 - headlight switch (pin 1, thick black/yellow wire) - fuses - lights

I get no voltage at the lights or across the fuses (with the light switch on) however I do get 12V at pin 1 on the switch. I also buzzed out the wire from the switch to the headlight and that's OK so this means it has to be the switch, right? Very odd. The switch lights up and everything so who'd have thought it was the culprit?

Was the switch the culprit?
Both my dipped beam and sidelights stopped working last night. Reading through the posts I've checked that I've got voltage at pin 1 on the light switch, but nothing at fuse 23/24 with the lights turned on - am I correct in thinking that this indicates the that the light switch has failed?
There's a switch on ebay (for a car with fogs, which mine has) but it appears to be only the centre dial - is this correct?
The switches can fail indeed.

The lights on the dash will come on, along with the interior night lighting because this all gets turned on when the side lights come on.

The switch has mutliple positions which engage different contacts to turn different things on.

As the dash light and interior night lighting come on with the side lights, they will still work even when you move the switch to the dipped beam position.

The black and yellow wire you refer to is the one that feeds the LHS headlight and the thick yellow feeds the RHS headlight from the headlight switch. Have you checked these at the connector level of the light switch with the ignition on and dipped beam switch on?

Thanks for replies chaps...I bobbed round to Mike's on thurs eve and swapped out the switch for a new one and...they still don't work.
Bit odd that they all went at once. I drove 8 miles to a friends house in the dark with lights working, came out, turned the ignition on and the headlight switch, but no headlights came on...other than running lights and full beam. Bulbs all OK, fuses all OK too...
Would the relay cause both headlights and sidelights not to work?
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Got it sorted now. It was a combination of a failed relay, a dodgy wiring block (the o/s headlight electrical connector block wasn't clicked back into position) and one blown bulb. Actually sorted for about £20 at the end of the day. Fairly easy once I realised how to use the multimeter set on 50V DC, tested at various points with headlights turned on and live (red) on the connector point and black on the chassis (earth). That looks blindingly obvious written down but amazing how aprehensive I was before starting...
FYI Audi relay part number 8Z2 941 531 E has been replaced with A7M0 951 253 A £14.16 inc VAT.
This thread was a great help to me with my A2 so I am adding my fix in the hope it helps someone else. My dipped bulbs stopped working one day mysteriously too. Relay 9 seems to power the fans too, and everything else on the A2 was working so relay 9 was ruled out. Swapped the bulbs and re-connected the wiring blocks to the headlamps to no avail. I took the headlight switch out by turning the lights off then pushing the light switch in, then popped the few bits of plastic cover off it which was fairly simple to do with a flat bladed screwdriver. I saw that the metal contact for the dipped beam was black and the nearby plastic had melted. By turning the light switch on and off you can identify which contact moves to activate the dipped beam. Scraped the bits of plastic away with a Stanley knife to fix the dipped beam.
Did the same as TurricanII - dissembled everything to the last bit out of that switch. "popped a few bits" - took me good 15 minutes :) But after cleaning the contact everything worked. Thank you everyone for posting your fixes.