nize

hi guys, on my 1993 audi 90 quattro, the dash lights, parking lights, and glove box light all went out at the same time. i've already verified all of the fuses and relays seem to be okay. i've also verified all of the bulbs are okay.

does anyone have any ideas what else it could be? many thanks in advance!

Audicted

First guess = your ignition switch. After that, have you installed an aftermarket radio recently.

nize

Audicted, thanks for the quick reply!

are you referring to the ignition switch that is activated when you turn the key or is there a different ignition switch somewhere? how can i test this?

regarding the aftermarket radio, i bought this car used and the previous owner had obviously installed an aftermarket radio (and subwoofer, and amp, and speakers) but removed it prior to the sale, so i got the car with no radio installed. could there be an issue with the radio wiring?

thanks again for the quick reply!

Solid20vq

Yup, pretty sure the ignition switch is behind the lock cylinder in the dash. In my car, a 1990 90 (B3), this switch is accessed by removing the trim panel under the steering column and then reaching up behind the ignition cylinder and unscrewing the switch, which can be identified by 3-4 red wires, 1 black wire, and one yellow wire, I think, it is only one or two phillips screws to take it out. After unplugging the wire connector from the switch, I would use a multimeter to test continuity of different points in the switch in different positions.

I am really just making assumptions here though, as it may be different for your B4. Also, I would search the forums for this same issue/symptoms because there is probably an easier shortcut-way to do this, but, ignition circuits are generally easy to figure out otherwise.

The switch has three positions: The first is basically off, there should be no continuity between any of the red wire and black wire positions in the switch. The second, or middle position is Power On, and it powers all of the systems of the car. This position should provide continuity between one-two red wire(s) and the black wire. The third, spring loaded position is Start, and is a control circuit which engages the larger starter circuit with a solenoid. I think there should be continuity between all/many red/yellow wires and the black wire(ground) in this position.

Hopefully you are able to find a decent source for electrical information and/or service/testing procedures for your car, as I said, maybe there is a better way to test it. If you do not have a multimeter (amperage, voltage, resistance tester) perhaps you can pull the switch and take it into an Audi tech and ask them to test it for you. It should be a relatively cheap replacement if you pull it out yourself, and potentially even cheaper if there is an alternate VW part (VW P/N) that would do the same job for half the cost.

Best of luck, hope this helps

nize

thanks again for the quick reply, i do have a multimeter and some basic skills so i will remove the ignition switch and test it today.

i'm just curious though, shouldn't the parking lights turn on even with the key out of the ignition? every other car i've owned allowed the parking lights to be on without a key, so i'm assuming the audi 90 should behave the same way.

just to clarify, the parking lights do not turn on at all, even though all bulbs, fuses, and relays appear to be fine.

i've done some searching through the forums and it seems the ignition issue usually affects the headlights, turn signals, and window wipers. on my issue, the headlights, window wipers, high beam, turn signals, and hazard flasher all operate okay, which seems to point to the ignition relay being okay.

the parking lights is what doesn't work, and seems to be connected to the dash lights and the glove box lights.

thanks again for your help. please let me know if anyone has any more ideas!

Audicted

You'd be amazed by how many circuits are affected by the ignition switch. At this age they're going bad pretty frequently so there'll be lots of posts on it. To know if your switch is bad, all you have to do is look at it. You'll see the broken part once it is removed from the lock barrel. Under normal circumstances, your park lights will come on without the car being switched on (another clue that is leaning towards a bad switch). The procedure outlined above by 'Solid20vq' is pretty close to what is prescribed for removing the switch.

CRAZY_RUSSIAN

ignition switch, then trunk wiring harnes

maineman

agree to that

nize

it looks like that switch is only $6 so i've ordered a replacement and will just replace it to rule out this possibility.

it also seems this same part fits some vw and porsche models.

i'll keep this thread updated with how it goes!

nize

switch part 4A0905849B ordered! should arrive later today or tomorrow!