My 93' f150 headlights worked prior to installing a western plow. I had my neighbor mechanic do the switch for me. It came off another 93' f150 and he switched wires identical to the original (which worked). Ive needed it when it has been dark this year so I have been trying to fix it.

I switched out the relay switch and plug in the cab. I checked all fuses. Only the headlights dont work, turn signals and running lights work. When the plow light harness is pluged in, those lights dont work either, only one running light works. I took out the 40 amp fuse in the power box under the hood and put my multi-meter on the connectors and got nothing. So I think no power is going to the fuse box but have no idea where to start on that and I am not too proficient with a mulitmeter...any ideas??