[Richard]

Use the control from one harness or the other. I would recommend using the fuel pump and fan control from the PSI harness. The commands will come from the ECM. You will get the prime cycle and any other features to shut off fuel pump in needed situations. PSI fuel pump output is from a relay, wires from that relay can go directly to fuel pump. Think circuit is fused at 30 amps.

The output for fans on the PSI harness (low fan/high fan} are triggers to ground for relays. Relays must be used as the circuit cannot handle the current draw of fans. How you wire the relays for fans is another thing. There are threads that talk about the subject in this forum.