I recently purchased a 1991 300E and discovered that some of the interior switch lights stay on after the car is turned off. The car is stock and completely unmolested with the original Becker and one (female) owner before me. Here is what I know so far based on the trouble shooting I've done:

With the key off:
the radio works and the antenna goes up
all window switches and fader illuminate
the headrest, rear dome lamp and defroster switches illuminate
the power door switch memory indicators ("1,2") are lit

With the key on everything works as it should.

The circuit is Fuse 9

Wiring diagram 130/3 points to block X6/1.

Block X6/1 is fed from the Instrument Illumination Control Unit (004 545 08 32) which is located behind the cluster and this is the part I believe to be at fault.

The one thing I don't understand is why the shift illumination would not be lit as well. Shouldn't everything on X6/1 be lit?

Any electrical trouble shooters out there that can help me out? Thanks.

Matt.

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1984 380 SL (Helga)

I replaced the Instrument Illumination Control Unit and everything is working as it should. This part is located behind the cluster, RH side.

Actual PN on the part I pulled is 003 545 63 32 and I replaced with an earlier version from an '89 with the PN referenced in my first post. the units look different but the pin numbers and plug are the same.

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1984 380 SL (Helga)