[Jack21]

Good lesson Excaliber.

Grounding. The starter solenoid case needs to be grounded, or it won't work. On a steel bodied car, it is almost a non-issue, until the mounting screws become corroded.

On a fiberglass car, or piece of wood, the case needs to be grounded, typically using a black, not red wire.

As stated above, the large connecters are used to power the starter through the solenoid (another name for a relay). The always hot side that goes to the battery is (or can be) used for an electrical pickup terminal for the rest of the electrical system.

The small terminal (marked "S" I think), powers the solenoid from the ignition Start switch terminal. A simple test for this is to touch a hot wire to this terminal while the case is grounded. The solenoid will "click", and on the other terminal, nothing will happen.

Also, as stated above, the second small terminal is ONLY used on older ignition systems that used ballast resistors in series with the ignition coil circuit. Electronic and CD ignitions do not use this start-only feature, as they run on full battery (or system) voltage all the time.

On the photo above: One large terminal (either one) should go to the battery. All other always hot system connections can be made here. The other large terminal gets connected to the starter only. The small terminal connects to ignition switch (or button) start. Nothing at the other small terminal. Ground lead coming off the solenoid case should be black to avoid confusion.