In my Porsche cayenne s 2005 the left side xenon low beam and both side cornering lights not working , i replaced the cornering bulbs and checked them on the head light assembly working fine before putting them back in the car , also the xenon low beam is working fine when i swapped the xenon bulb and the control unit(ballast) left to right , also i replaced the outer 2 wiring harness and all the inner wiring harness of the head light assemblies ,

 

It could be a lose connection. It happens to my 04 CTT on and off. I just tap the light slightly and it works again. You could try to tight the headlight again by loosen it a bit then push back in little hard and tight it up.

ALX5

 

Where did you find the internal wiring harness? I've had problems with my headights with the insulation becoming brittle and cracking off.


Are you sure the plug is getting fully seated back together when the assembly is "locked" back in place?. That seems to be a common problem with these.


Also like I mentioned, if you haven't looked at the wiring inside the actual headlight assembly that would be where I'd check. If you replaced it all I'd suspect maybe a crossed wire or short like Alx5 mentioned.


And know on the cornering lights if one goes out for any reason they both stop working.