i have a 82 1-ton dually i was trying to figure out why my dash lights were inop so i was using constant power from the fuse panel then the wire got loose and touched the printed circuit and melted part of it. i have dual gas tanks and when i switch to the left take it goes way past full i had since replace the printed circuit from a truck that doesnt have dual tanks and it still does it when i push the switch to go from tank to tank i can hear theswitching valve working what else could it be the sending unit?
