I'm having some trouble diagnosing a tail light issue. When I turn on my head lights, the left side tail lights turn on but the right side tail lights don't. Both sets of brake lights work fine. I swapped the bulbs over and still have the same problem, so the filaments aren't the issue.

I also checked what I think is the tail light sensor unit (a small rectangular box with an 8-wire connector going to it, near the tail lights) and there was something rattling in it. I took it apart, resoldered a resistor and replaced some nasty looking solder too. Hooked everything back up, but I still get the same problem.

And yet another thing I found while doing all this is my reverse lights aren't working either. Replaced the bulbs with known good ones, still not working.

Any ideas?

 

It turns out one of the resistors in the sensor unit was fried, so I replaced it and tail lights are good to go now. The reverse lights still don't work though, so any insight on that would be great. Not sure where to start with those.

 

I did some more testing. The connectors going to each side of the center panel get:

No power when keys are out (makes sense to me)
12V key in ON position, trans in reverse
4.5V key in ON position, trans in neutral <-- wtf?

I also checked for continuity through the two circuits on the center panel, all good. Visually checked the bulbs and seemed okay. Not sure where to go from here.