The wiring of the YJ isn’t too bad, but oddly enough I could not find a standalone harness, so we just made the factory harness work. We only used the engine side of the firewall harness, and we deleted most of the headlight wiring because we will install a new body harness from Painless Performance. There is a wire that powers the EFI ECU and another that engages the starter. The tricky part is figuring out which is which. After a power probe, a wiring diagram, and a phone call to a few friends, we tracked them down.