Crazy2, thanks a lot. The plow is a Meyer E-47 mounted permanently on the truck. Aune, tracing the wiring was tough because the second owner put the plow on and installed the wiring himself, but the connections seem tight. I wouldn't know where to start taking pictures!
The switch that selects plow or truck lights has 6 terminals. the center 2 come from the trucks wiring, one is high beam one is low. With the switch in the truck light position it routes the power to the (bottom?) 2 terminals and when on plow it routes to the (top?) 2 terminals. If your truck lights are working it is not a problem with the truck but the plow wiring. The Meyer site has troubleshooting, install instructions, etc. You can find a wiring diagram there.