Starting System: Description and Operation

STARTER SYSTEM
The starting system cranks the engine at a speed fast enough to permit the engine to start.
^ Heavy cables, connectors and switches are used in the starting system because of the large current required by the starter motor while it is cranking the engine.
^ The amount of resistance in the starting circuit must be kept to an absolute minimum to provide maximum current for starter motor operation.
^ A discharged or damaged battery, loose or corroded connections or partially broken cables will result in slower-than-normal cranking speeds. These concerns may even prevent the starter motor from cranking the engine.
^ In case of starting system difficulty, the operator may have discharged the battery before calling for assistance.

The starting system includes the following:
^ permanent magnet gear-reduction starter motor with a solenoid-actuated drive
^ the battery
^ ignition switch
^ Transmission Range (TR) sensor (automatic transmission)
^ clutch pedal position switch (CPP)(manual transmission)
^ starter relay
^ heavy circuit wiring
^ Vehicles equipped with a manual transmission have a clutch pedal position switch in the starter circuit that prevents operation of the starter motor unless the clutch pedal is pressed.
^ Vehicles equipped with an automatic transmission have a transmission range sensor in the starter control circuit, which prevents operation of the starter motor unless the transmission range selector lever is in the NEUTRAL or PARK position.

Sequence of Operation
When the ignition switch is turned to the START position:
^ Voltage is provided to the starter solenoid. The starter solenoid is energized directly from the ignition circuitry. A magnetic field is created in the solenoid coil.
^ The iron plunger core is drawn into the solenoid coil.
^ A lever connected to the starter drive engages the drive pinion gear to the flywheel ring gear.
^ When the iron plunger core is all the way into the coil, its contact disc closes the circuit between the battery and the starter motor terminals.
^ The current flows to the motor. The starter drive gear cranks the flywheel and the engine crankshaft.
^ As current flows to the motor, the solenoid pull-in coil is bypassed.
^ The hold-in coil keeps the starter drive engaged with the flywheel.
^ The starter drive remains engaged until the ignition switch is released from the START position.
An overrunning clutch in the starter drive protects the starter motor from excessive speeds during the brief period before the driver releases the ignition switch from START position (as the engine starts).