This is identical to the problem I have except I haven't gotten as far into the troubleshooting as you have. I'm going to give this a try asap. Thanks for posting it up!I've been trying to run down starter and battery problems for a while now. It turns out that the first thing I unplugged was the ScanGuage2 plugged into the OBDII port. The ScanGuage wasn't going into sleep mode and was pinging the multiplexors at the gauges. It was pulling 2amps with the car off. Ruined a battery (fortunately covered by warranty). Replaced the starter and unplugged the ScanGuage and all better. The manufacturer stands behind the product so I'm going to send it to them along with the cable and they'll sort it out for me.