I have a 2004 ram 2500 and am adding a 2nd fuel tank switched through a 6 port valve. the lift pump has been upgraded to in tank. I have installed a second pump for the 2nd tank. I need to know what wire from the ignition triggers the main tank fuel pump relay so I can switch off the main tank pump when I switch to the 2nd tank. My concern is deadheading the pump when I switch tanks