Interesting problem- passenger map light dim and won't turn off?
 

Got in car tonight and instantly noticed the passenger map light (not the dome light that comes on when the doors are open, but the switch only map light) was dim and flickering. I never use the light, so I toggled it on and it went to full brightness. I toggled it back off and it goes back to dim/flickering. Shut off the car, and it stays on indefinitely.

Anyone had this issue before? I don't want to take it back to the dealer. Even though it's under warranty I would rather fix myself if it's easy. Unfortunately I can't think of anything that would affect a single map light other than maybe water getting into the switch from a leak in the sunroof.

You have a short somewhere. Start looking for damaged or crossed wires. Could be a defective switch. Possibly a bad bulb but unlikely.

The problem is most likely the mechanical On/Off switch.