Tail lights and license plate lights are out.
Brake lights, rear fog light, turn signals, reverse light, hatch release, window defroster, and rear wiper all work.
Ran a test wire directly to the tail lights from a 12v socket and they all lit up, so bulbs and grounds are fine.
Sometimes when first turning the lights on, they illuminate very dim for about 2 seconds and then go out. Sometimes they don't come on at all.
Fuses for associated items look good. There is not a fuse specifically listed for the tail lights. However, other Volvo models mention a relay for the tail lights and licence plate lights.
My best guess on a 2006 is F58 "Right high beam; auxiliary lights relay; 7.5A"
I'm thinking it could be a bad relay. Where is this relay located?
The wiring diagram clearly shows that it is not part of the CEM.
If it's not the relay, any other ideas for what it could be? I'm about ready to run a new power wire to another ignition power source if I can't get this figured out... Can't drive without tail lights.
Edit: Just noticed that the city lights and parking lights are also out. So it's definitely something associated with all of the auxiliary lights.