LS SWAPS: Wiring Harness and Wiring Guide - LS Engine DIY The wiring aspect of any LS swap is undoubtedly the most difficult. Most builders are familiar with fabrication techniques, trouble shooting, and parts swapping to make things work, but electronics rise to a much higher level of complexity. LS Stand Alone Harness | eBay All wiring harnesses are plug and plays, which means you do not have to program them to your vehicle and as soon as they are installed, they are ready to go. When shopping for your LS standalone harness, browse through the large inventory available on eBay. Adding a wiring harness to your vehicle makes plugging in wires a snap.