tracing wire on slide switch

This past weekend i discovered that the switch that extends the kitchen slide is not working. Hand cranked the slide out no problem.

i pulled the cover off and see red and white wires to the little circuit board. using my 12v test light I determined there is no power to the switch,.(i had already tested the fuse and that was good).

now for the dumb part, how do i trace those wires to the source? i've crawled and poked all over but can't find them..........argh

2006 Coachmen Leprechaun
29' 2 slides