Jeep Wiring Harnesses | Quadratec Whether you're completely re-wiring a Jeep, or just adding a few accessories, a pre-made wire harness can make the job much easier, and more professional looking when you're done. Painless wiring offers both universal kits and Jeep model specific kits so you can get your entire Jeep wired. Jeep Chassis Wire Harness - Engine & Transmission Wiring The purpose of a Jeep YJ wiring harness is to deliver electrical and other information to places your rig needs it. Many of the Jeep's systems have their own wiring harnesses. For example, your rig has a Jeep transmission wiring harness and an engine wire harness assembly. Unfortunately, over time, wiring harnesses can wear out.