Below are the descriptions of the main circuits when doing starter test:
NO.1: This is where the battery positive cable from the battery is attached to.
NO.2: This is the S terminal of the starter Solenoid. This is where the Start/Crank wire is attached to and the one that delivers the 12 Volts from the ignition switch when you turn the key to Start.
Some vehicles will use a nut to attach this circuit to the starter Solenoid.
Other vehicles (mainly Japanese cars & trucks) will have a female spade terminal instead that mates to a male spade terminal.
NO.3: The grounding point. The starter motor is grounded through its case.
