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Car is a 1983 300SD. First time its been in to our shop. The owner was complaining of a battery drain problem. We narrowed it down to the power seats. The odd thing is as follows:

-Key off, door open, power seats SHOULD work, but they don't.

-Key off, door closed, power seats WORK.

No wonder that relay was hot when we pulled it!

For the life of me, I can't find the diode. It's not in the fuse box, as I expected.

Anyone who might shed some light on this?

P.S.---The car is an immaculate example, never been modified, one owner with under 70K original miles. Matter of fact, after 20+ years of ownership, the gentleman decided he no longer preferred the MB-Tex upholstery so he had all BRAND NEW leather seats installed at an MB dealer. I asked him if the problem cropped up after the seats were put in but he said it was present before.

:confused: :confused: :confused:

The wires that pass through the door jam are most likely the problem. My right rear power window had a similar problem.

It sounds to me like the front driver door switch is not working correctly. I'm using Alldata and it shows that the door switch is supposed to be closed when the door is open and open when door is closed. The switch grounds the control side of the power seperation relay.

Pin 85 on the power seperation relay socket should be grounded only when the door is open.

I don't see any diode in the power seat diagrams.