I'm sorry for butting in, but I looked up this code in the Ford PCED:
DTC 1451 is for an electrical fault in the cannister vent solenoid circuit. The canister vent solenoid is mounted to the charcoal canister above the spare tire.
If the circuits check out good (No shorts to ground, power or opens) you probably have a faulty cannister vent solenoid.
There should be an EVAP canister mounted above the cross member where the spare tire is mounted (it's a cylindrical shape, black and plastic). The Canister vent solenoid just snaps into the evap canister. If you just see a 2 wire electrical connector hanging there, that would be causing P1451. I'm 100% sure that this truck has a canister vent solenoid because I have repaired many P0457 (Small evap leak detected) DTCs caused by this valve not being properly seated into the evap canister on Rangers, for some reason they pop loose.
Looks like someone removed it from the truck.