Very random. Sometimes the tail lights work fine. Sometimes only one of the two bulbs work. LH upper buld and RH lower bulb will light.
Checked grounds, fuses all good.
Every time I've been at the dealer I've asked for help, but the dangs things were working fine. So no help.
I agree with STIAJW that these are often grounding issues, but intermittent electric issues are difficult. Years ago I had the exact same issue but the volt meter always showed 12 volts. It was a ground issue that allowed a trickle of juice (enough to show voltage on the meter) but not enough to power anything. Could also be a connector issue.
Upon further thought (don’t laugh! I’m old), since you aren’t blowing fuses I would lean towards a connector. Either wire or to the bulb receptacle. Had an 87 Chevy that had an error code set only during cold weather. Borrowed a mobile oscilloscope and traced to a single wire - crank position sensor. Followed it everywhere and it was perfect. Took that wire block off that connects the wires thru the fire wall. Plugged it back in and it never happened again.
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