Looking at the solenoid, the battery cable goes on the left large terminal, The 12V start line goes on the small terminal next to the battery terminal (usually marked S ). This is the 12V that comes from the ignition switch when you turn it to start, and energizes the solenoid. The next small terminal (usually marked I ) is a 12v output which is only there while the solenoid is energized. It goes to the + side of the coil, or to the electronic spark module if you have electronic ignition, to put a full 12v to the ignition system for hotter spark when trying to start the car. The last large terminal goes to the starter motor.
