The 1947 - Present Chevrolet & GMC Truck Message Board Network

To me it sounds like more the swich itself. Get one from a dealership or a AC Delco store. Most auto places don't carry it. I went ahead and got a new cover while I was there with the speed nuts (make their own thread on the plastic studs). Take out the ashtray and unbolt it out of the way. It's a PITA to get to but there are two studs that the speed nuts are threaded onto. Best way is to unplug the wiring harness to the plug and move out of the way. I ended up breaking my switch cover studs (hence the new cover ;) ) and take out the switch. Then place the new switch in the way the other came out making sure driver and passenger side being the same position as before. Then place the cover on and turn the nuts on the studs. They will be hard to turn but they will make their own threads.

If this doesn't solve it then the valve be bad. Easy way to check it is take a test light to the wiring. The valve is under the passenger side near where the cab and bed meet inside the frame rail. Not sure what wiring setup you have on that truck but if it was like mine it's a green wire going to it. When you flip the tank switch to the driver side it powers the valve to take from the driver side. Mine ended up being a loose wire on the fuse panel (pink with black stripe) that powered the switch itself. If it's the one wire setup this is the easiest way to check- take the green wire off and take the test light to it to see if it comes on with the key turned over (not running) and the driver side switch pressed. If it doesn't come on then it's either a wiring issue or a fuse. If it does come on then it's a bad valve.