Here's the skinny...
The switch is a momentary reversing switch. The contacts don't actually make until the switch is depressed fully (in either direction). When you let go it springs back, and all contacts then go open, even though it appears the switch is up (or down).
Looking at the face of the switch, or the female connector behind the switch I have the following (on Mine, '81):
Upper left- Light Green wire = one side of the gas valve motor
Upper right- Dark Green wire= The other side of the gas valve motor
Lower right- Pink wire= Fused Ign B+
Lower left= Black wire= Ground
Here's how it works
When the switch is depressed fully in the up position:
Pink (B+) is connected to Dk Grn
Black (Gnd) is connected to Lt Grn
When the switch is depressed fully in the down position:
Pink (B+) is connected to Lt Grn
Black (Gnd) is connected to Dk Grn
Basically what you are doing is reversing the polarity at the motor, making it go the other direction. A side note- inside the valve itself is where the fuel sender signal from each tank is sent to the gage on the dash. It is possible that the valve is actually shifting, but the switches inside the valve itself aren't switching the sender inputs to the gage. I would check the electrical first:
With ignition on, and the dash switch removed from the connector:
Confirm 12V between Pink and Black. If not, bad fuse/ wiring.
Confirm 7-8 Ohms between Dk Grn and Lt Grn. If not, open wiring, bad gas valve motor
Confirm switch operation: Fully pressed should short the switch teminals described above. If not, bad switch.
Call me if you have questions. Gotta run, Parker awaits.... yeeehaaa
