Starting System: Description and Operation

STARTER SYSTEM

NOTE: Engine oil viscosity can affect engine cranking speed.

The function of the starting system is to crank the engine at a speed fast enough to permit the engine to start. Heavy cables, connectors, switches and a starter solenoid (attached to the starter motor housing) are used in the starting system because of the large amount of current the starter motor requires 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 battery, loose or corroded connections, or partially broken cables will result in slower than normal cranking speeds and may even prevent the starter motor from cranking the engine.

If the starter motor or circuit is suspected of causing a no-start condition, use the diagnostic chart and the appropriate tests to diagnose the condition. Testing and Inspection

Sequence of Operation

NOTE: An overrunning clutch in the drive assembly protects the starter motor from excessive speeds during the brief period before the driver releases the ignition switch from the START position (as the engine starts).

1. The ignition switch is turned to the START position.
2. The starter solenoid is energized, creating a magnetic field in the solenoid coil.
3. The iron plunger core is drawn into the solenoid coil.
4. A drive lever and pin connected to the drive assembly engages the starter drive to the flywheel ring gear.
5. 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.
6. The current flows to the starter motor, and the starter drive cranks the flywheel and the crankshaft.
7. As current flows to the starter motor, the pull-in coil is bypassed.
8. The hold-in coil keeps the starter drive engaged with the flywheel.
9. The starter drive remains engaged until the ignition switch is released from the START position.