Take a look at the charger board. It has a 13 pin connector on it with
a harness that leads to the connector at the back-center of the main
board. Notice the pattern of the wires in the charger connector.
(1)–(4)–(7)(8)-(10)(11)(12)(13). The dashes are empty. Start
counting from the position that is closest to the front of the truck.
Add 1 amp, 250vac fuses to positions 1, 4. Then add 1/4 amp (any
voltage)fuses to positions 7, 8. One and four is the AC voltage going
to the main board. Seven and eight is the pwm that goes from the main
board to the charger.

The last 1 amp fuse goes to terminal #19 in the junction box. If you
look at the schematic you can see which side to add the fuses to. Some
say the side with the tiny gauge wire. But when I do mine I will be
adding it to the side with the pair of large gauge wires. One wire of
the pair comes from the 12v aux battery, the other wire goes off to
the Magnecharger.