Main Beam Flash
 

Hi all,

I'm kinda guessing that cars from other countries have this same feature so apologies up front if this isn't an issue for anyone else.

Basically, my main beam work when on permanent (stalk pushed back) but not on flash (stalk pulled forward).

I've put a request in a British forum but haven't had any luck - http://forum.a8parts.co.uk/showthread.php?t=7464

I think this it is probably a relay but that means there must be two and I don't know where either are. Can anyone help me locate the main beam relays?

Thanks in advance, Matt.

1st, when asking for specific help, include the year and country of the car...many things change from pre-facelift to facelift models and drive sides.

Because I'm a smart guy :) , I'm assuming you have a RHD PFL ('98 or before?) model.

The car only has one lamp control module (large relay)...see drawing below. which shows 2 locations in the relay panel, but is actually one large relay covering the 2 spots. In LHD models, it is in the large central electrics panel under the passengers footrest panel.

There is only one pathway (wiring) from the bright/flasher switch to the lamp control module. The only separation is 2 sets of contacts in the switch itself.

I'd put my money on the switch...not the module (relay).

http://i1217.photobucket.com/albums/...d.jpg~original

Thank you for the reply and I apologise for not adding that. It is indeed a 1997 PFL car. It is a RHD 4.2 Quattro Sport.

Sorry to sound stupid (I'm not a smart guy when it comes to cars!), when you say you think it's the switch, do you mean the switch in the stalk?

The reason I didn't think it was that was because of the change in voltage at the bulb plug when I pull the lever (videos in the UK forum post).

Thanks,

Matt

His suggestion of the switch (stalk) is probably correct.
 

the switch inside the stalk is a common failure point amongst various models in the late 90s-early 2000s. I recently experienced a failed switch, its a 30 minute fix.

In this video you can see the two switches (white). what happens is the white plastic melts slightly, preventing the contact point from conducting the current properly.

Inspect both pieces of plastic for melted areas. If you find melted plastic, trim it away so the contacts can engage properly.

Sorry, I only looked at the first video which seemed to show no response from the pulled back (flash) position.

1st, as I understand (from videos), you have the meter connected at the headlight connection (behind the bulbs)?

If so, it looks as though the problem could be with a connection there...maybe passengers side only(?). I'd look closely at the contacts in the connector and on the bulbs themselves...maybe even try a new set of bulbs.

I may have read this wrong, but wiring diagrams show that the high beam circuit doesn't even pass through the lighting module or any relay, just a simple on/off circuit at the switch and separate dedicated fuses for left or right high beams.

Again, judging from your tests, a problem at the headlights (connections/grounds) themselves...not the switch or light relay.

Just a long distance guess from the info available.

Thank you both for your help, it really gives me something to go on. I'll have another look this weekend and let you know.

Matt

Sorry I should have also answered your question too.

I have the meter connected at the main beam connection behind the bulbs. In each of the videos I tried all variables, one with the left bulb out, one with the right while the other two have both bulbs out but the meter in either side. I'm not sure if you can see the spreadsheet attached to the same post but the readings were pretty consistent. I therefore thought it must be the bulbs but I asked at a local motor factors and they said because they work in permanent (stalk pushed back) then it won't be. I think they are upgraded bulbs so I may well try some normal halogen OEM type too.

The melted plastic contamination of headlight switches was a common issue in the original Audi V8s (1990-1993 because Audi wired directly from the switch to the lights. Those of us with those cars resolved the issue by installing relays between a power source and the lights that were triggered by the wiring from the switch. That, of course, was after either cleaning or replacing the switch.

On RHD models it is also under the passenger footrest panel (ie. left hand side).
Ironically the fuse panel is still on the right hand side, restricting footwell leg room and causing Audi to never offer a manual gearbox in RHD models... pity.