Bench test tank selector valve?

[bnoon]

The passenger's side tank and lines have been removed from my truck by a previous owner and the selector valve has been bypassed. The selector valve ports have all been capped which leads me to believe that it may still work. Is there a way to test it besides just hooking it up? I'm going to have to clean it and get a wiring clip/pigtail to put it back in service anyway (as well as buying the tank/lines/etc), but I don't know how to test it.