you beat me to it...it is for security, not to tell you you didn't close the hood all the way. Remember, if you try to tow the car, open a door, or the hood, so on and so forth...the alarm will sound...probably why it had voltage to it, because it wasn't making a connection. Once connected, the voltage shouldn't be there because it has made a circuit. Just the opposite of what you would think, but that's how an alarm works.