1999 SL500 Dome or courtesy light switch not working. It is located near sunvisor. It has three positions. Left shows a door, which should turn on all lights when the doors are opened. center is off andright is turn on all lights when I push button. This switch does not work at all. The courtesy lights at the bottom of the door do work and come on when I open the door, and the map lights do work when I push the map light button. Any suggestions anyone ?? Thanks in advance.

AL in NJ

 

I would removethe maplight assembly and then remove the 3-position switch and test it with a basic electronic multimeter. This switch can be purchased by itself. If the switch is good, then I would assume the circuit board inside the maplight assembly is bad. If that is the case I would examine it closely and look for cracks in the solder traces.