I have a 2001 mustang GT with an automatic the previous owners apparently headed for 6 months off of car lot and the car broke down he had it towed in and they told him the mechanic shop that the wires are reversed on the alternator so the wires were reversed on the alternator and it turned up some wires on the harnesses not too much but I replaced harnesses,I replaced the fuel injector harness and the fuse box harness the ECM and the gauges and what's going on now the fuse box is staying on all the fuses are lit up under the hood and the dash is coming back on the gauges are turning back on with the key off and odometer shows lines going through it the traction control button light is lit up I can't read the computer from my code reader and it kills the battery I heard about your back up and it runs fine like a raped ape so just to recap I replace two harnesses fuel injector harness it goes to the big plug underneath the hood the fuse box harness the ECM and the gauges seemed like it worked at first for about 45 minutes. and then went back to doing what it did