TM-9-2320-387-24 HMMWV Direct Support & General Support Maintenance Manual Volume 1 Download
Page 303 of 1205
TM 9-2320-387-24-1 2-36. STARTER CIRCUIT TESTS The starter circuit consists of the batteries, starter solenoid, starter motor, rotary switch, parts of the Protective Control Box (PCB) and related electrical wiring. The relationship of these parts is shown in the block diagram below, and a simplified functional flow schematic is provided on the foldout FP-15. The starter solenoid and starter motor are enclosed in housings to protect them from dirt, icing conditions, and other road hazards. When the rotary switch is turned to START, the PCB checks if the engine is running. If the engine is not running, the PCB sends a signal to the starter solenoid which energizes the solenoid windings and causes the solenoid contacts to close, sending battery power to the starter motor. The battery power causes the starter motor pinion gear to engage the engine flywheel ring gear and the engine cranks. When the engine starts, the rotary switch should be released, allowing it to return to the RUN position. This tells the PCB to release the starter solenoid which, in turn, disengages the starter motor from the engine. PROTECTIVE CONTROL BOX I 1 ALTERNATOR + A < z STARTER F SOLENOID -: STARTER 4- ROTARY CONTROL 4 A SWITCH CIRCUIT 1 f 1, 4 STARTER 1 t ENGINE MECHANICAL 2-247