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As title says, I had a BFM warning and a tail light that was sometimes ok and sometimes not.
Replacing bulb made no difference but a wiggle of the socket would make the bulb "flash" on and off.
Cleaning the socket had no effect so I decided to melt the plastic retainers on the socket mount to remove the circuit board.
When I saw the circuit, it was pretty obvious what the problem was - both the running light and back up bulb connections were VERY starved of solder and the running light connection was cracked to boot.
A quick reflow of the joints and all was back to normal.
Not sure if I've encountered this issue before, maybe someone else had this problem in the past?
The rear bulb holder, driver's (LH) side Tail light socket upper left, intermittent Melting plastic nipples to release circuit board cracked and starved running light connector at far right reflowed joint circuit board reassembled, plastic nipples re-melted.
Over the years I've had problems with tail lamps in our '93 that would stop working even though the bulbs were fine. I've cleaned the sockets and bottoms of the bulbs and pulled up a bit on the center terminal of the socket, and all has been well for awhile, but I think you've probably identified the real problem! Next time it acts up I'll follow your lead.
Must be a fault in production, those joints were very sparsely soldered!!
Maybe the QC guy was asleep (again!)
They must have been soldered by the same guy who did the BFMs, TCMs, ABS modules and fuseboxes. I wonder if his coworkers called him "The Solder Miser."
Nice job. I've fixed so many things with a soldering iron. While these old XJs have a ton of relays and circuit boards the individual solder joints are huge and easy to fix.
I had a problem with my taillights just going out and not setting a BFW. The hardest part was figuring out which relay controlled them. When I found the relay and looked it up there was a core charge on the relay so I new it was repairable. 5 min with a soldering gun and done.