Wiring a head unit is easy. Just remember it needs a wire for its memory for things like the clock and station presets and that means constant power, which is usually a yellow wire from the head unit. Then it needs to know when to turn on so you don’t have to install another switch and that one is a red wire most of the time. The last of the three most important wires is the ground, and that one you already know. It is black. We talked about speaker wires a couple of months ago, and the only one you care about after that is the illumination, which is normally orange. Recently, I’ve been leaving that one unhooked and just manually setting the head unit for “dim” because of how bad some of these Jeep’s electrical systems are.