TM 10-3930-653-14&P 4-7-3-1.  STARTING MOTOR 4-7-3-1. DESCRIPTION The function of the starting system, consisting of the battery, ignition switch, starting motor and solenoid, is to crank the engine.  The electrical energy is supplied from the battery, the solenoid completes the circuit to operate the  starting  motor,  and  then  the  motor  carries  out  the actual cranking of the engine. Fig. 4-151.  Starting Motor 4-93