He cleaned the terminals (they were pretty corroded before), the wires were good, and he even put a new Northstar battery (northstarbatteries.com) in the Jeep because it kept saying “check battery.” He figured the battery that was in the Jeep when he got it was 10 years old, so better safe than sorry. However, the big problem was a loose nut right here on the power distribution center. I found it and laughed at him a lot. But we still only got 13.4 V with the Jeep running. I guess I have more searching to do.