baris41

Hey guys, i have this problem for couple of days now, drivers side low beam is not working, blinker is okay though. I already checked the bulb and fuse (f66), they seem to be okay. Should the issue be ballast or is there any other option to look into?

rapidoxidation

first swap the bulbs from left to right and right to left. If the problem remains where it was, then swap the ballasts in the same manner. If the problem follows the ballast, you know where the problem is.

Heguli

Remove the bulb, and see if there's a white ball inside of it, 1/2" or 13 mm or so from the tip. If there is, bulb is gone.

baris41

I swapped the bulbs, they are okay. Might there be any other option other than ballast?

baris41

Silly question, if i made a shop to check the error codes, would it spot the faulty part?

rapidoxidation

With the right code reader, probably. I doubt the free reading they do at parts stores would catch it though.

F1Fan

Carefully check the wiring. There have been reports of the wiring insulation coming off and causing issues. Be very careful when doing this.

juanmor40

For example an internal break of the wire within the insulation, the wire looks OK from the outside, but under tension, it does not work.

You may disconnect it from the bulb. measure the voltage at the connector and it passes, but when connected it may be in a different position, stretching of the harness to reach the bulb, bending, etc and it fails again. A nasty intermittent issue sometimes.

baris41

It turned out ballast is out, now i need to order a new one, but there are 3 different part numbers, which one to use?

juanmor40

post your VIN number, and likely Konigstiger will, as usual, provide you all information you may need from original to latest part number.

bbirdwell

Or go to mbepc.net, search by your car's Vin, when the data card page comes up the top block will have a description of your car such as w211.074. in that block click the hyperlink to take you to the parts catalog. There you can search in the electrical section and find the part numbers that apply to your car. It may show several different part numbers but it will also show the early part numbers were superseded by a later part number. Any of them will work however. If possible, however, get the latest part number you can as it has the latest improvements.

konigstiger

Headlamp adjustment CU part # is 2118709026 replaced by current 2118705585.

baris41

For future use; i ordered the part on Aliexpress. It's much easier to replace it through fender guard/lining (30min) instead of removing front bumper.