dan-needabimma

Got in my car last night to enjoy a good friday night and my lowbeams don't work all of a sudden.

The running lights that come on with the first click of the selector switch work and my highbeams work; but neither lowbeam comes on.

Occassionally when I flip the switch back and forth, I can see the cluster lights flicker as if there was a power draw trying to turn the lights on but the actual lowbeams don't even flicker.

They worked the night before!! The bulbs are aftermarket Silverstars but I can't imagine them both blowing at the same time and only blowing the lowbeam element...

Where should I start?

Quattrotrac

I would start with both the ignition switch, and the actual headlight/cruise switch. On the 5k cars, the headlight switch, turn signal, cruise, wipers are all one big switch. I'm saying ignition switch because of the power draw you're describing.

It's a good idea to visually inspect the wiring harness of each headlight to see if anything obvious has gone wrong, even though it doesn't seem likely that both bulbs caused a problem simultaneously.

Start with the switches and repost if they don't solve the problem.

Your battery light, or any other trouble light on the dash, doesn't come on while driving does it?

dan-needabimma

The only thing that was done to the car since I saw the lights working last was a brake fluid flush and I don't think there's any headlight wiring in the area of the resv...

Randolph

If you have the European lights you most likely had the relay go bad. I've BTDT, it caused my low's to not work.

If you have the stock lights I'd check the multifunction switch, and general wiring. I thought I read somewhere if you go with too high wattage of bulbs in the stock setup without running relays you run the risk of frying the switch since all that power goes through it.

Randolph
87 5KCSTQ
93 928GTS

Kneale Brownson

I never had this problem with the 5ktq, but on our first V8, we had the same symptoms. Problem is too much resistance in the switch as the wiring ages and the wires in the connector to the switch get hot enough to melt the plastic surrounding them. The plastic settles on the stud of the switch, coating enough that it loses the connection.

First order of business is to relay the headlights. Then you MAY get away with cleaning the connection on the switch. I used a fine cloth-backed abrasive to try to get rid of the plastic on the switch and a fine wire brush to scrape out the female connector in the wiring harness. This worked for a while, but I could feel the assembly warming up when the lights were used, despite the relays, and the whole thing scared me. A friend's Audi burned up after it started smoking behind the steering wheel. Anyway, my final solution was to replace both the switch and the wiring harness connector. We've driven the car several years with this solution.

I relayed my 200q20v's lights as soon as I had the V8 issues. The V8 we bought a year ago gets relays as soon as I finish the timing belt and brake hose replacements.

audiqv8

I had this problem with my 86 5KTQ and the fix was to replace the switch used to turn on the lights on the steering wheel. None of the lights are relay so the full current is going through the switch and after years of arcing the switch eventually fails.

dan-needabimma

I replaced the headlight switch with a known good and the lights are still out...

On my way home from work yesterday I stopped at a gas station; could see in the window that my lights were still out when I parked. Got back in my car and whoa! my lowbeams were working. I went out last night and drove 30 mins to my destination and parked. Got in the car and drove 20 mins or so, all of a sudden the lowbeams go out while I'm driving...

Happened probably ten times that night but they didn't stay off. It didn't flicker like there was a shorted wiring coming loose over bumps or anything, it looked like a very deliberate off for 2-5 seconds and immediately back on.

I'm somewhat confused... If there is no relay/control module/fuse for the headlights and the high/lowbeams use the same bulb, how is it possible I only have a problem with the lowbeams???

dan-needabimma

I would assume they are stock but there have been 5+ other owners of this car...

Quattrotrac

First, there are separate bulbs for the US DOT headlights on your car. The low beams should run 9006, and the high beams (bulbs closest to the front grille) run 9005. There is a headlight relay on your vehicle. You need to test it, or just change it out with a good one.

Generally, when low beams don't work, it's the switch. You've changed it, and the result is intermittent lights. My guess is that the low beam wiring harness (yellow wire) is either frayed or not making connection somewhere all the time. It's affecting both lights at the same time, so if the wire is the fault, it'll more likely be somewhere at the switch, not at the headlights.

Check the wiring and see what happens. Get a voltmeter. When the lights go off, test the yellow wire and see if any current is coming through. If it is, something is up with either your switch or headlight relay.