Success!

So, I installed that relay I purchased and to my surprise still no headlights, I didn't expect that to happen. That lead me to believe that the light switch was the issue. I took apart the bottom section of the dash on the drivers side, removed the switch and tested it, it passed. I really didn't expect that to happen. The only cause now would be a wiring problem being the cause, located somewhere in the dash. Unfortunately since there are so many wires in that location it really wouldn't be possible to find out the issue. I figured that I would at least jiggle the wires to see if that might do anything, make a connection in someway, and to my surprise it did. I now have working lights.

As compress ignite put it "The DMM (Digital Multi-Meter) will tell all"

Next time I'll take the time in the beginning to test the whole system to find out where the problem lies, in this case that would have fixed the problem.

Thanks for all the help everyone!

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1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500

On my 300se the left beam would go dim after some time , it seemed like i bad ground or a corroded pin , everything was cleaned and reinstalled but the fault persisted.
I removed the ' good' fuse on that section and simply replaced it with a fresh brass tipped one. Fault rectified. I looked at the fuse under a magnifying glass and it became clear why the fault existed . The alloy tip had eroded away with age .I Replaced all the fuses with brass tip ones and so many rare And intermittant faults disappeared.
mak

On my 300se the left beam would go dim after some time , it seemed like i bad ground or a corroded pin , everything was cleaned and reinstalled but the fault persisted.
I removed the ' good' fuse on that section and simply replaced it with a fresh brass tipped one. Fault rectified. I looked at the fuse under a magnifying glass and it became clear why the fault existed . The alloy tip had eroded away with age .I Replaced all the fuses with brass tip ones and so many intermittent faults disappeared.
mak