If your Jeep doesn't like to start up in the cold or the idle is rough until the engine warms up, consider installing a Jeep Manifold heater relay from Painless Performance®™. This kit allows you to install a manifold heater during your rewiring process. It is completely compatible with a Painless Performance®™chasis harness and can be used with later style manifold on an older Jeep. For more information about this wiring harness, check out the online instruction manual.