Dash lights!

[greg.cranwell]

After much thought I started working on my car again after ignoring it for the last few months.

None of my dash lights up currently, none of the switches, the instrument clusters or the gauges. Doesn't bother me during the day however at night it's a bit rubbish! Fuses are all fine and I've had a few bulbs out which appear fine.

Any suggestions or wiring diagrams available if I was to try and replace some wiring and get this sorted? It's not the biggest problem I have but its one I have been putting off since I bought the car.

1990 b3 coupe quattro

Cheers for any help!

[mikes2]

The dash and switch lighting is controlled from E20 which is in the cluster itself.

it's a dimmer switch but if it's broken it can give zero output.

Does the glovebox light work ? The same green / grey wire which feeds the glovebox light also feeds the dimmer control switch. It comes from fuse S14.

[greg.cranwell]

E20 within the clocks, so if I remove them and check if this is burnt out? I will check the power to the glovebox light, if that has power, I'm guessing I could bypass the dimmer switch and wire everything from somewhere else if this is the fault.

I'll play around tomorrow and see how I get on cheers!

[greg.cranwell]

So the fuse for the glovebox light is blown, should be 5amp. I have put up to 30 and it keeps blowing so something has gone wrong somewhere, guess it's a case of tracing wiring until I find a fault unless there is something common?

[mikes2]

Jut check the wires aren't touching each other. The wire for the glovebox light comes across the rear of the console so if it has rubbed through the insulation the fuse will blow easily.

if you need any photos let me know. I've got my entire dash out just now

[greg.cranwell]

I've pulled the dash forward so I can get to everything, traced the wires to just by steering column and lack of daylight has forced me to stop but so far they look fine. Will continue to follow the wires along to check them later this week when I have a chance.

I hate wiring.

[greg.cranwell]

Wiring from glovebox light, all the way to the yellow plug going into the clocks looks fine.

What part do I test on the clocks and how please?

I will slowly get it fixed!

[mikes2]

The small white device in the bottom right of this pic arrowed

[leggy]

Originally Posted by greg.cranwell

... I've had a few bulbs out which appear fine....

Had an issue with the clock back light on my 80...
Like you, the bulb 'looked' fine, but after swapping two of the bulbs about just to be sure and in making the problem worse, I then checked both of the bulbs that I'd swapped with a multimeter and it revealed that they were both in fact defective!
I've since replaced 'all' of the backlight bulbs with new ones and everything is now lit up as it should be; also tested all of the old bulbs and have the good ones stored away safely in a tin just in case I ever find myself needing to replace one in the future.
The moral of my story being, that, I took that darn instrument panel out maybe 4 or 5 times before the problem was finally diagnosed/fixed, something that I could have avoided if I had only had the multimeter and some new bulbs from the offset.

[greg.cranwell]

Cheers, got new bulbs on the way and failing that will look for new speedometer