Looking at the 01 service manual, at the wiring diagrams for the headlights, I don't see the headlight relays, that are in the PDC..... except for the quad headlight systems.... I don't have quad headlights, I do have a relay in the PDC labeled "headlights", and a spot for a second one.... Which is just a tad confusing.

In any event, back to the point of this exercise, it appears that the headlamp switch provides the ground path for the circuit...... I could see rewiring the circuit so that the headlamp switch actually DOES simply control a relay, and have the heavy load on a shorter wire run, thru the relay......

Thoughts?

 

To fix that issue I bought a heavy duty wire harness from LMC truck (had to change two wires to make it work right) so the headlights no longer draw power from the switch. Plus I added a relay for the marker lights as well cause the seemed to be the first to go on my truck.