The 38 pin jumper is also self powered on my car. I kept a same charger on the battery while getting into the modules, all had some sort of codes that I cleared, now I will see what comes back on restart. Amazing tool that will be hard to give back. I saw a few selling for 1199.00,
. I have yet to check to see if the roof works, I would love to turn off the back O2 sensors, just after the cats. May I ask, are you a mechanic or hobbyist?