I guess you don't have the puddle lights as fitted to the 300E then...

You'll need a 12 v feed that is only live when the door is open, so your best bet is probably to tap into the interior lights circuit that is activated by the door switch. You may be able to get a direct feed from the switch itself.

The window motor feed is live when the doors are open, yes, but is also live when the ignition is on and the doors are closed, which may explain why its blowing your fuse.

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1987 300e manual 250,000 km (sold)