I have 1989 300sel.

I shorted some wires when tried to install a new cd-player. Now the center console lights (including all window switches on the doors) are always on with max brightness even without the key in ignition switch. Can change the brightness on the instrument cluster only with the dimmer. I guess dimmer is fine
so is dimmer fuse.

Please help

What are the details?
Do you mean that by shorting wires that the you think the head unit is connected wrong? Or did wires melt and cross? Do your console lights have power when your head unit does not? Does your antennae work?

This is a long shot, but one way you could have done this is the following: If your cd player has a lead wire for dimming its own display and you were attempting to connect it to the wire that controls your dash lighting, but instead connected the wire for your antennae to it, they would be on anytime your head unit has power. Very few (and mostly only very new) head units actaully pulse power through the antennae lead - it is constant 12v.

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1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick

the console lights are powered without the head unit because i didn't install it yet. I isolated each wire in central console to be sure I don't have shorted wires.

I don't know what to tell you other than retrace your steps. Did you cut any wires or undo anything? If you did not, I'd take it in to someone and have it fixed as you will waste more time than the money it will cost trying to figure it out.

By the way, I'm headed your way for Wintergrass at the end of Feb.. What can I expect weather-wise?

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1982 Mercedes-Benz 300CD
1982 Mercedes-Benz 240D - stick

The problem was with the instrument illumination control unit or solid state controller (don't know the exact name for it) located right behind the instrument cluster. What happened was that the circuit in the illumination control unit got burned and shorted input wire (from the fuse box) with output wire (to interior lights) after I shorted some wires behind the radio. That's why I had my interior lights on all the time.

I'm attaching the instrument panel wiring diagram for 87 560sel.
May be it’ll help somebody in the future.
It definitely helped me!

By the way, if you are going my way expect raining weather-wise.

Attached Files

560sel_87_instr_pnl.zip (47.7 KB, 48 views)

Thanks for the follow-up. Really important for the "cure" to be posted, so we can find the fix in the archives when one of these arcane problems arise. Good sleuthing!

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)