Description & Theory Of Operation: Identification: Solenoids

There are generally four electrical terminals located on the back of the solenoid. The two larger terminals are the battery terminal (upper) and starter motor terminal (lower). The two smaller terminals are ignition switch terminal (marked "S") and ignition coil terminal (marked "R").

NOTE: Not all solenoids have an ignition coil terminal. For example; late model vehicles with high energy ignition systems do not use ignition coil terminal (marked "R").

NOTE: On Motorcraft Positive engagement starters there is no solenoid mounted on the starter motor, instead there is a starter motor relay usually mounted on the fender well next to the battery. A starter relay is used because of high current requirements. The relay is located so that the heavy connecting cables are short and will conduct heavy current flow with a minimum of voltage loss (drop).