Starting System Operation

Voltage is available at all times through the BLK (2) fusible link at the Battery Junction Block and the RED (1442) wire to the Ignition Switch. When the Ignition Switch is held in the Start position, battery voltage is applied to the YEL (5) wire to the I/P Fuse Block. CRANK Fuse 20, if it remains continuous (not open), supplies this voltage through the PPL (806) wire to either the Transmission Range Switch (Park/Neutral Position And Backup Lamp Switch) for vehicles with automatic transmissions. If the vehicle has a manual transmission, the voltage is applied to the Clutch Pedal Position And Cruise Control Shutoff Switch.

The contacts in the Transmission Range Switch (Park/Neutral Position And Backup Lamp Switch) are closed when the automatic transmission is in either the Park or the Neutral position. With the contacts closed, battery voltage is applied on the YEL (1737) wire to the coil of the Starter Relay at Pin 85.The contacts in the Clutch Pedal Position And Cruise Control Shutoff Switch are closed when the clutch pedal is depressed. With the contacts closed, battery voltage is applied on the PPL/WHT (1035) wire to the coil of the Starter Relay at Pin 85.

The Starter Relay's coil is grounded from Pin 86 by the BLK (150) wire to the engine grounds. With voltage applied at Pin 85, the Starter Relay coil energizes and closes the relay contacts. Battery voltage is available at all times from the Generator terminal through the RED (1542) wire and the BLK (1542) fusible Link. When the relay's contacts close, battery voltage is applied on the PPL (6) wire to Terminal S of the Starter Solenoid.

The Starter Solenoid has two coils or windings. The Hold-In Winding is grounded at the mounting bolts. The Pull-In Winding is grounded through the Starter Motor. Both windings are energized when voltage is initially supplied from the Starter Relay. The combined force of these windings operates the solenoid plunger to move the shift lever mechanism. The movement of the shift lever mechanism engages the Starter Motor with the flywheel ring gear. This mechanical operation is described more completely in the description of the Starter.

At the same time that the solenoid plunger is operated, contacts with the solenoid close. Battery voltage is available at all times to these contacts from the Battery through the BLK (1) wire. This wire at Terminal B of the solenoid is sized to handle the current flow needed to start the engine. The closure of the solenoid's contacts applies battery voltage at rated current to the Starter Motor. The Starter Motor then operates to rotate or crank the engine.

The presence of this battery voltage applied directly to the Starter Motor through the solenoid's switch contacts causes the solenoid's Pull-In Winding to de-energize. Battery voltage is now available at both sides of this coil and no current will flow. However, the Hold-In Winding remains energized until the Ignition Switch is released from the Start position. When the engine starts, the driver releases the Ignition Switch and the Ignition Switch returns to the Run position. This removes the voltage from the Hold-In Winding and the solenoid's plunger retracts. This, in turn, disengages the Starter Motor from the flywheel. At the same time, the solenoid's contacts open. This removes battery voltage from the Starter Motor and the Starter Motor stops operating.