I made a serious OOPS and forgot to follow rule #1 of electronics: disconnect the power first.
I checked the 12v source to ground with the car off completely and it had power, so it wasn't an ACC line. Great, so I just mistakenly swapped the wires now I'll swap them back!
One blue spark later and now there's no power on that 12v line and my car won't start. Did I just fry my ECU?
