Pin 807 / wire number 24 on the A5 card is the ignition start wire, stick +48 volts on to this & see if the truck starts up.

There is +48 volts on pin 805 / wire number 21 from fuse F60 you can use.

F60 should be the top 10 amp fuse in that fuse holder inside the motor compartment.

I take it you have stuck your hand up the dash & checked the keypad is still plugged in, I have had one come undone before where people like to have a fiddle.