I'll do a brief timeline of what's happened as its pretty ridiculous!
1. Bought a 2014 Mercedes GL63. The passengers side headlight had a dull led strip (drivers side was fine and the dash was throwing up a warning light).
2. Researched it online and came to the conclusion it was simply the module.
3. Ordered a chinese copy, fitted it, didn't work.
4. Ordered a genuine used one, fitted it, didn't work.
5. Took it to a coding guy. Didn't work. Was told it's the headlight not the modules.
6. Completely fed up, i bought a genuine used headlight (no modules included).
7. Fitted the headlight with brand new D1S Osram bulbs, used old modules, but the led strip still the same (dull).
8. Tried the drivers side module (i know i should have done this at the start!) on the new unit and it lit up properly (so it was a module afterall and I had had bad luck purchasing 2 faulty units previously!)
9. Ordered another chinese copy module (same one as step 3).
10. Before fitting the chinese copy module, I went for a drive at night and noticed the new headlamp high and low beam working in reverse
constantly on high beam and when I pull the stalk it goes down to the low beam. The bulb/plug can only be fitted in 1 direction. The other headlamp was working correctly as always.11. Fitted chinese module and the error went from the dash and LED worked
. However, the high/low beam issue (working in reverse) was still present 
11. Took it to my mechanic, unplugged it, took the bulb/module out and fitted it to the old headlamp to test. High/low beam working fine on the old unit with the same bulb/module. So it must be an issue with the headlight.
I'm at my wits end with this. To think I had the correct solution from the very start but was sold 2 faulty units and then bought a full headlamp and found it to be faulty too! You couldn't write this!
Do anyone have any ideas? Is there anything that can potentially be done without having to remove the whole unit again (bumper off job!)? Maybe modify wiring etc so it works the other way round? The wiring can be unplugged quite easily through the arch liner and is accessible.
I really don't fancy taking it all apart and fitting the old headlamp for 2 reasons; a) it has a foggy lens and has dirt on the inside and b) the car clearly has had a bump at some point on that side so removing the bumper again will no doubt result in brackets and stuff breaking. It was a pain doing it once and if I can avoid doing it again, i would be much happier.
