It is probably not the switch itself. The problem is more likely in the Smart Entrance Control Module which controls the timed interior lighting functions. Download a copy of the FSM if you don't already have it and look on page EL-92 for the lighting module section.
Did you check the panhard rod? You said you replaced all four trailing arms, but didn't mention the panhard rod which does the side to side location alignment. Your symptoms point to the panhard rod as the culprit.
I've got an '02 QX4 which is basically a loaded R50 Pathy. The backlight in my nav/climate control unit went out. Turned out that the cheapest solution for me was to have a custom CCFL bulb made to exactly replace the original. I'm not sure which years Pathy contained the same touchpanel, but the ...