I have a 1994 XJS V12. When I get in the car and turn on the lights, at times the low beams will not turn on, just the running lights. If it is dark, I have to turn the brights on just to be sure I am seen. After driving for a short period of time, I can turn the brights off and the low beams appear to be working just fine.
Does anyone else have a similar problem, and are there any ideas about how to fix it? Also, my tail lights seem to be.....inadequate. Can I replace the tail lights wit LEDs ? Can I replace the headlights with LEDs?
Thanks.

 

The headlamp relay is failing. Mine was doing the same thing. I removed it from the car, opened the cover and noticed some cracked soldering. Typically, if you see a dark space around the weld, those are cracks. Take a soldering iron to them and reflow the soldering. Worked like a charm!

 

Actually, I replaced the headlamp relay and it did not fix anything. Everything else looks fine. My brother thought it might be a short in the low beam wiring but so far I have found nothing.
Of course, it does not help that this problem is intermittent, so it is difficult to tell if something fixed it or it is just behaving itself for awhile.

 

I still think the module needs to be looked at. Open it and look at the solder joints. Mine was intermittent also. Otherwise you will continue to keep guessing. Even the replacement is guaranteed to have cracked solder joints. Just open it and look, before you start looking at wiring