Shortly after purchasing my XJ8L, I noticed that the interior lights were not fully operating. Just the front foot well lights would come on, the rest of the interior remained dark. It's a big enough car you never know what could be lurking in the shadows, so after looking up the fuse for that section (#11 in the trunk fuse block, 5 amp) I tried a fresh 5 amp fuse which promptly blew out. Taking a small risk, I then tried a 7.5 amp which allowed the rear ceiling and foot well lights to come on, but the front foot lights went out and the whole thing would cut out for a second about every 6-7 seconds, also the front console light never came on.
Ok, now the main suspect is the front overhead console and thanks to the forum for direction on how to remove it. It does help to have one of those plastic trim removal hooks to help pull the leading edge from the headliner as the sharp edge WILL REMOVE SKIN (experience point)!
Once down, I noticed that the bulb housings stay fastened to the ceiling while the switch gear plugs in on each side as a fixed point to the assembly. Tightened the connections to the pin by tweaking with a small screwdriver, probably small needle nose pliers would work as well, made sure the connections were clean and replaced the dome bulb as a preventative measure. Carefully installed the overhead console, making sure the pins lined up with the connections as much as possible (hint, make sure to shove the console as far back onto the headliner shell as you can, it's a tight fit.) and as the French say "voila", the interior lights now work completely and correctly using the proper 5 amp fuse. Best of all, I didn't have to drop the whole headliner to trace a short! (Been there, done that, American vehicle's vanity mirror harness meltdown.) Not entirely sure if it was a bad connection or just a bad bulb, but if two solutions are cheap enough to save the time, try them both. In this case all it cost was some research time and a bulb. (and aforementioned skin)
It is one of the most beautiful views in the evening to see all that gorgeous wood and leather properly lit up.

 

You've got some great cars! What's your favorite?

 

The Ambassador is my favorite "bomb around town on Saturday" car, while the Volvo is the best relaxed driving car. The 67 Mustang was actually bought for my wife during our first year of marriage following a plan I call, "If you like having a bunch of old cars around, buy an old car your wife likes and restore it first!" Married over 20 years now, almost up to a car per year. I guess it's working.