13. The Turnkey wiring harness is an easy way to swap an LS engine into your early-model truck or buggy. The harness comes ready to plug and play and simply requires 12V power, ignition, a tachometer, a fuel pump, and fans. The Delphi computer has been programmed with a Turnkey proprietary calibration and uses factory connectors for everything down to the electric fan controls. It is packaged in a marine-grade harness.