I searched and searched. Couldn't find anything that speaks to this subject directly: 3 Wires go to the harness to power the Fuel Shutoff Solenoid Part Number AM124379, RED BLACK and WHITE. The Red HOLDS, Black is Ground and White is the POWER that PULLS IN the unit. Testing procedure; provide power key on with Seat control bypassed. Turn the key on and off and test for voltage accordingly on each, red and white. If you have battery voltage; then buy a new Shut off Solenoid*. IF NO POWER on either RED or WHITE; Put your fingers on each of the TWO relays and verify that both click, the LEFT relay is the PULL IN RELAY the RIGHT is the GLOW PLUG RELAY. IF THERE IS NOT 2 clicks, then check the grounds, but you'll have to buy a new CIRCUIT BOARD because this is a solid state unit. The old part number for the CIRCUIT BOARD is AM115249. It has been revised to AM120740. The revision requires a new harness plug, AM136628. My circuit board had a loose pin.
* Shut off Solenoids, seem like they should never wear out, but heat will kill them.
* Shut off Solenoids, seem like they should never wear out, but heat will kill them.