[Scott quail]

The red and black on the left side is your 48v. Red wire to the same big post as the yellow one was on. Black on left side is 48v neg. Goes to main negative battery post which is the last negative in the series of batteries. The yellow wire is the 12v POS. This hooks to your headlight positive which i believe is the red on the harness. And the 12v black can go to the neg side of the solenoid. Im assuming the neg for the lights is on the solenoid so instead of ohming it out to figure out which one, just put it on the NEG side of the solenoid. First thing first. Check the red wire on the harness. If no voltage, confirm with continuity that its your headlight wire. Since it was hooked to the reducer id assume it is. If it is indeed your headlight wire, hook the 12v pos to it and the other wires where i stated. Should be good to go