Last night, my son's '04 F150 started having problems with the lighting system When he turns off the engine, the flasher lights come on (although with a low illumination), as do the cab overhead lights and some of the dash lights. He also says the cab lights stayed on when he drives (he could not turn them off) and the dash lights were much brighter.

He had a new stereo system installed a few months ago - although the light problem just started yesterday. Not sure if the there is a connection.

Any ideas?