Neil, good point. I didn't even think about using the switch to turn the engine over without starting..i.e., over the winter when you give her an MMO treatment, and certainly don't want to start her up, but may want to spin her over to move the oil around.
Mary, I didn't see your link but it sounds like we have the same ~$10 Actron model from your local auto boutique. It is a simple switch that is closed when the trigger is pressed and open when not. When you press the trigger, you are closing the circuit between the "S" terminal (white or yellow w/ red stripe wire ) & the big battery terminal, and that energizes the starter...the same thing that happens when you turn the key to start.
