XJ40 Rear Turn Signal fix, diagnosis w/o a voltmeter
 

Well, when checking for what vehicle lights worked and didn't work, I noticed my driver's side rear were not functioning at all. The fronts worked and so did front/rear passenger side.

So, I opened the boot and located the relay module and gave it a gentle rap with my finger knuckle and nothing happened. I did it again and the lamps flashed once ne'er to repeat.

I moved to the bulb holder and removed the cover by unscrewing the two knobs. There was the socket board held on by another two knobs. I gave it, too, a gentle rap and it blinked, then stopped.

I removed the socket board and noticed an attached harness plug to the board. I disconnected it. It looked good so I reconnected it. The lamps blinked once, then stopped.

I then noticed the socket board was attached to its plastic housing via heat welded (over the end) plastic studs. It would be easy enough to disassemble with a Dremel but I thought it would be a moderate pain in the butt to reassemble with screws (after first drilling concentric pilot holes) - especially so, if the socket board proved not to be the problem.

I put it on my "things to remember to look for" list and later found a used socket board. I put it in service and the turn signals work now.

Talk about things that make you go, hmmm.

https://www.jaguarforums.com/forum/a...1&d=1314672914
Jaguar XJ6 Tail Lights Bulb Holders 88 - 94

I won't throw my original one away. Someday, I'll take it apart and figure out "what's up" with it. I suspect a starved or broken solder joint.

o