The instruments panel lights either are all on or all off. Lately mostly off.

I pulled the instrument panel out of the dashboard and while looking at the front of the panel, there is a small square box in the bottom left-hand side (it has one screw in it). When I squeeze this box or flick it, all of the instrument panel lights come on for a brief time. Then after some time, all the lights go out.

Anyone know what that is? If you had the instrument panel in, it in the direction of behind the left button that resets your mileage trip ( but I don't thing this box has anything to do with it).

In any event I would like to have my instrument panel lights! It's dangerous driving in the dark.

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1990 Mercedes 300 SEL (320,000 miles)
1994 Mercedes E420 (140,000 miles)