Starting System: Description and Operation

STARTING SYSTEM

The starting system consists of the:
- starter motor.
- starter switch, part of the ignition switch.
- transmission range (TR) sensor.
- starter motor relay.
- starter solenoid.
- starter drive.

The starter motor:
- is a permanent magnet, gear reduction, 12 V dc motor
- has an integral starter solenoid.
- has an overrunning clutch in the starter drive.

The starter drive:
- is operated by the starter solenoid.
- engages the flywheel to turn the engine.
- has an internal overrunning clutch to disengage the starter motor when the engine starts.

The starter solenoid:
- is an electromagnet.
- engages the starter drive to the flywheel.
- when energized, contacts close, connecting the battery to the starter motor and causing the starter motor to turn the starter drive.
- is kept in the energized condition by a hold-in winding until the starter switch is released.

The starter motor relay, located in the battery junction box (BJB):
- controls current to the starter solenoid.
- is engaged by the ignition switch.

When the ignition switch is turned to the START position, the starter motor is energized, connecting the battery to the starter solenoid.The starter solenoid moves the drive lever to engage the starter drive with the flywheel ring gear and connects the battery to the starter motor.

The TR sensor prevents starter motor engagement unless the transmission is in the NEUTRAL or PARK position. Refer to Transmission Control Systems.