Making good progress with "re-wiring" the inside of the cab. Normally I would keep the original trucks wiring harness for lights, gauges, horns, wipers, etc but this 78 truck was missing most of it's wiring when I got it. Typically I just cut down the mid-90s harness to be a "stand alone" harness for operating the engine and transmission, but instead I'm using it to operate the entire truck. I'm finding it's surprisingly easy so far to move all the 78 controls onto the wiring from the 96 donor. Wire colors and stripes haven't changed much between the decades. So far I moved the key switch without much issue. I added an extra relay to carry the load of the heater circuit versus running that through the key switch. The 78 key switch is "lighter duty" than the 96 which is why I added the external relay circuit. I moved the turn signals off the 96 multi-function switch onto the 78 turn signal switch, moved the high beam selector off the multi-function switch onto the 78 floor switch and I moved the wiper motor and controller from the 96 to the 78. The 78's wiper motor was MIA so rather than source a replacement I just moved over the 96. The only modification was turning the arm on the motor 180 degrees so the motor would clear the heater ducts of the 78. The last piece of the wiper puzzle is to move the control wires onto the 78 switch. I haven't compared schematics for the two years yet to see if the delay functions match but I'm sure they'll be close enough. Right now I'm working on moving the heater controls from the 96 to the 78. Only difference here is in 78 the resistor pack was between the battery and the fan motor and in 96 the resistor pack is between the fan motor and ground.
This is the "core wiring" update. After this is complete I have to figure out what I'm going to do with the gauge clusters. The goal is to keep everything looking like the original 78 stuff as much as possible.
