The relays are the way to go. Takes the load off the headlight switch. Works the same way the lift pump relay upgrade works.The headlight switch has a bimetallic strip in it that when over heated bends and opens the circuit. If you wait a few minutes it will cool off and close. It will get worse until it totally fails. My headlights are on relays as well as my driving lights.
I think that theferm said that temp was about 140 degrees.View attachment 63210remember I put twin 170 thermostats in it.. I may not remember correctly but I thought somebody said the torque converter doesn't lock up until a certain temperature and this truck runs really cool since I switched the thermostat which was quite a while ago... I don't remember if it was about the same time as I did the brakes and tranny change