So my story is when I opened a driver door overhead light and door step light will not come on. So today I took my volt/ohm reader and jump into. Passenger door is working properly. So I don't getting 12 V at switch in the door. I swapped switches and same thing. I have good ground from switch ground wire to car ground (use metal part of the engine start switch).
Than when i was reinstalling everything back, I noticed passenger switch will activate some relay. I was just playing with it, I heard clicking sound under the hood. Looking at attached diagram below M to K6 pin 6 is relay called Power seat window. I removed it, check , it looked fine no visual burning marks, just very old as see. Than re-installed and none reading or overhead light were working, emergency light didn't work too, radio/cd player stopped working, sun visor lights didn't work too. I drove as is few miles and suddenly radio came back and else too. Very strange. It's like something didn't energized for some reason.
I would not touch this relay anymore, it really should not effect door light anyway, left door will not active this relay, no clicking sound on this relay.
So looking at schematic, N2/4 is faulty, may be diode? Is anyone experience with this before ?








Thanks

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91' MB 350 SDL, with 961 engine and #14 valve head
09' ML320 Bluetec