Daytime running lights
 

Hi everyone. After a few years of debating whether to buy a Mercedes, I finally came across what I felt was a good deal.
I just picked up a 1997 E420 in mint condition, with only 94,000 original KM. This is my first Mercedes, and even though I like to work on my vehicles, I really don't know that much about Mercedes. I bought this car for my son, and before I can get it safetied, I have to fix the DRL on the passenger side.(Driver's side works, passenger doesn't) Switched the bulbs, same thing.

Read on another forum where it could be the actual switch, so I bought another control switch and installed it and the same thing, driver's side works passenger side doesn't. Has anyone else experienced this? Does anyone have any suggestions as to what I should be looking for, Pictures, Diagrams?
Thanks,
George