[Fulltiming]

Unless an owner added the relays later, the wiring goes through the headlight off/on switch then to the low/high beam switch at the base of the steering column activated by the left steering when stalk, then to the headlights. The adjustment is somewhat sensitive on the low/high beam switch. Newell recommended that I just replace the switch. On my 1992, it was a 1989 Chevrolet Truck part number 26019660. Your '86 may have been from an older pickup but it could be the same switch. Mine got to where I could adjust it for high beam or for low beam but not where it would work on both settings. The new switch works fine and wasn't that difficult to adjust.

Adding relays does a great job of reducing voltage drops.