2003 xc90 my tail lights stay on and drain my battery (not brake lights) tried turning the light switch to all positions and no other lights are affected. no luck, has been damp and raining if that has anything to do with it. any suggestions? thanks grm

 

Just the rear parking lights? And not the front ones also? Left side front and rear is on fuse 32 in the c fusebox (on the end of the dash) right side is fuse 33. The signal to both rears also goes through the REM (rear electronic module) and there is a relay on the CEM that powers the fuses. (and all 4 bulbs)

If all corners are lit - first check power at the fuses for the fronts may not be working due to bad bulbs - there may be a problem with the CEM, the relay or the Light switch module. If only the rear bulbs are on and there's no power at the fuses- that could be a problem with the REM turning the lights on by mistake.

 

yes, thank you, just the rear tail lights

 

If there is no power at #32/33 fuse - the REM is turning them on at the wrong time. I trust you have removed #32/33 fuse and the rear lights still stay on. By the way the tag lights are on fuse 33 - they should be on if the CEM is sending power, not if the REM is doing the wrong thing. Tag lights are 10/3 in the diagram.