Hello, kinda stuck for a minute on this one. Just bought my 2004 XJ8 recently and the main headlight beams did not work. Replaced the bulb and right side wiring harness after removing the bumper and headlight assemblies. So now One headlight works but not the other side. Switched the rt. and lft. to eliminate the headlight assembly wiring itself. So both headlights work but left doesn't when connected correctly on the left side. And the high does work but not the main beam light. So that's where I'm stuck. The only thing I can think to do now is try replacing that connection that plugs into the headlight assembly but if anyone can point me in the right direction to save me some time and money, I'd appreciate it. Thanks, Larry p.s. guess I can take a pic and post later this morning after the sun comes up...

 

In my experience not related to JLR: when headlight work when only one headlight connected, and not when both, on working side ground is broken. Yes, I know it is counterintuitive.
However, short list of haphazard guesses:

• ground studs behind headlamps.
• main harness nor internal lamp harness is not damaged.
• incorrect ballast, bottom of headlamp
• try to swap left/right component to see if failure travel.
• improper headlights Xenon vs. HID

This is not a complete list. Assuming you do not have history if this new to you car, I would start making sure that components are the one that intendent for this car and function properly on their own.

 

Hey thanks!. I did notice what looked like a grounding bolt that was loose on the side that does work so I will tighten that first to see if that's the issue or at least eliminate that.

 

BE CAREFULL! Do not overtighten nuts on those ground studs! They may be already corroded completely. If stud breaks then you will have to drill and tap hole and thread new stud. Keep in mind that body of your car is not a steel. It is aluminum. It will form a galvanic pair with typical metals like stainless steel. Aluminum has higher galivanic number than nickel and iron, so aluminum will corrode; while if you take a bolt that is heavily zinc plated it will last longer as long as zink plating is not scratched.
Any way to not go for brass, stanless silverplated hardware to replace brocken ground stud..

 

I never overtighten but it didn't really matter. It wasn't corroded at all and apparently someone had just loosened it b4 for some reason. Wasn't the easy fix I was hoping for though. I've already come across very shoddy and lazy work right off someone has done before me so. The only next step I can see for me now is to try to test that connector that plugs into the back of the headlamp assembly itself then I guess replacing and splicing into the old one as it appears to travel way up into the top side of the car to I do not no where yet so. Thanks man, any tips are helpful!