Its a worthwhile project for certain. I did it and it was a tremendous help in seeing at night (I also moved up to H-4 Halogens).
So take a look at the factory wiring diagram and find where the hi and lo wires for the headlight switch run in the engine compartment along the inner fenderwell. Then look to see where the wires bifurcate to feed the left and right bulbs (usually pretty close to the radiator saddle and voltage regulator.) Unwrap the wires and find the split, cut the wires here. Install two 30 amp 4 pin relays (if you have room, above the voltage regulator horn relay on the back side of the radiator saddle), preferably water proof. One relay is for the low beam and the other is for the high beam. Sort out which wire is for high beam and low beam.
Then run the low beam wire that is from the headlight switch to the No. 86 pin on one relay and the high beam wire to the No. 86 pin on the other relay. You may have to extend the wires slightly to reach the relays.
Run a ground wire to each of the No. 85 pins. Then run two 12 gauge hot wires from the battery, with water proof 20 amp inline fuses, to each of the No. 30 pins.
Finally, connect each of the high and low beam wires that go to the bulbs to the No. 87 pins (both high beam wires to one relay and the other low beam wires to the other relay). Want to do it even better, run new larger 14 gauge wires to the bulbs.
Once its all wired up, test it. The headlight switch will now trigger the relays, and the relays will feed the bulbs a full 12 volts and a much brighter headlight (no parasitic loss through the headlight and high beam switch, and small stock headlight wires). If it works like is should, tape it all up like factory and you are all set. Its a really great conversion and one that makes driving these old trucks at night much safer for both driver and others on the road.
Last edited by Dragsix; 10/30/2019 3:06 PM.
