MB uR quattro instrument panel is dull

[4WDrifter]

The dash in my MB quattro doesn’t seem to be bright enough. There is a knob which is supposed to control the brightness which is turned up full and I suppose it could be faulty but I was wondering if the 3 bulbs circled in the photo are responsible for the backlight?
Then I thought I could try putting 12v across the correct terminals in the multi pin connector to see if the brightness was better but I can’t find anywhere a schematic for which terminals supply what. Can anyone help me? Thanks in advance.

[4WDrifter]

[4WDrifter]

Just found these— am I correct in thinking that 12v across 2 and 21 or 22 should illuminate the dash?

[Tractor Dave]

I had this issue on my last Ur. You can check the dimmer switch if you remove and use a multi meter. I did find a test thread somewhere. I will see if I can find it. My switch was fine. Unfortunately, it was something internal and Pete Knight sorted it.

[Tractor Dave]

This may help

http://www.classic-audi.co.uk/forum/showthread.php?t=39648

[4WDrifter]

Thanks Dave. By summer switch do you mean the rheostat knob which turns the brightness up and down?

[Tractor Dave]

Yes, sorry. Typo. Dimmer switch of course. My bl##dy kindle seems to love to change all my words for something random

[4WDrifter]

Yes, sorry. Typo. Dimmer switch of course. My bl##dy kindle seems to love to change all my words for something random

Well, some good progress for me. I tested the rheostat and the readings were all over the place including infinity ohms or no current at all! It appears that the uR quattro rheostat has 2 rheostats in the switch one 0-21ohms and the other side 0-60 ohms. It took a bit of trial and error to figure out which connections were which. Then I called into Halfords and bought a tin of electrical contact cleaning spray. Squirted it into the switch, let it dry in the heat of the sun and back to the multimeter. Big difference now but I was still getting zero current in some positions. So I bit the bullet and had a go at opening the switch and I could now see how it worked and I got the sliding terminals all nice and clean. I put it all back together and the resistance changed smoothly now as I turned the knob. Plugged the dash back in and connected the rheostat and for the first time since I bought the car I now have a bright orange dash. Result.

[4WDrifter]

This is one of the corroded terminals.

[Tractor Dave]

Nice fix

[newsh]

Well, some good progress for me. I tested the rheostat and the readings were all over the place including infinity ohms or no current at all! It appears that the uR quattro rheostat has 2 rheostats in the switch one 0-21ohms and the other side 0-60 ohms. It took a bit of trial and error to figure out which connections were which. Then I called into Halfords and bought a tin of electrical contact cleaning spray. Squirted it into the switch, let it dry in the heat of the sun and back to the multimeter. Big difference now but I was still getting zero current in some positions. So I bit the bullet and had a go at opening the switch and I could now see how it worked and I got the sliding terminals all nice and clean. I put it all back together and the resistance changed smoothly now as I turned the knob. Plugged the dash back in and connected the rheostat and for the first time since I bought the car I now have a bright orange dash. Result.

Excellent!

[sal_s2]

On a similar note, does anyone know where to get the 3 bulbs from for the illumination? NLA from audi

[newsh]

On a similar note, does anyone know where to get the 3 bulbs from for the illumination? NLA from audi

Hi Sal
You could ask Pete Knight, I would imagine he can source them, PM if you need contact details.

[sal_s2]

Yes John, can you pm me the details please?

[newsh]

Yes John, can you pm me the details please?

PM sent