Need a Fuel Tank Selector Valve

[rajincajintj]

Originally Posted by hatzie

I'd like to take back my comment about hooking to the firewall stud. I'd hook the 12v+ power connection in the diagram to an ignition switched 12v+ source. I modified the drawing to reflect this.

Why? You want to run the valve as little as possible. If the source is the battery and the valve is in the AUX position it'll cycle when you turn the truck on and off.

hatzie,

please dont take this the wrong way, but i don't follow you here. i would think you need a constant power source to keep the switching and operating of the valve to a minimum. if your 12 volt source is constantly going high and low (as the ignition does) wouldn't it cycle the valve every time the ignition turned on when the D wire has +12V power?

if you keep the +12V source constant, the relays and valve only cycle when the switch is turned, right?

i might be reading your schematic wrong and i definitely dont mean to poke holes in your suggestions, i just want to be clear on the purpose.
thank you for your support in this, man. you are already saving me potentially hours of under truck time.