James,

I'd have to really look over the diagrams as well, but the output to the other lights HAS to be isolated, either with diodes or multiple relays - otherwise, you would not have the fogs isolated from the parking lights. But I agree, I'm not certain how they isolate things.

HoneyB,

I know most MB dealers won't admit it is an SLK320 with a different body, but it is. What I tell people to do is find a local shop that advertises MB experience and expertise. The similariites in wiring between the SLK320/32 and other MB products is rather extensive. (And the mechanical similarities are almost 100% once you get to the drive train and chassis level).

In Atlanta, it's Buckhead Imports - wonderful bunch of guys. Any major metro area that has a similar MB population will likely have SOMEONE who will look at your car.
In my case, I often go to "Glover's Garage" - they don't advertise MB, but one of the owner's wives drives an SLK320 - he has grown to know the car. Her car has, last I talked to him, 170,000 miles on it.

Actually, I SELDOM take ANY vehicle to ANY car dealer's service department. I have only once had a good experience at a car dealer's service department.