GM Service Manual Online
For 1990-2009 cars only

When the Ignition Switch is moved to the START position, the battery voltage is applied to the Starter Solenoid, and both the Solenoid Windings are energized. The circuit through the Pull-In Windings work together magnetically to pull in and hold the Plunger. The Plunger moves the Shift Lever. This action causes the Drive Assembly to rotate as it engage with the flywheel ring gear on the engine. at the same time, the plunger also closes the Solenoid Switch Contacts in the Starter Solenoid. Full battery voltage is applied directly to the Starter Motor and it cranks the engine.

As soon as the Solenoid Contacts close, the voltage is no longer applied through the Pull-In Winding, since the battery voltage is applied to both ends of the Windings. The Hold-In Winding remains energized, and its magnetic field is strong enough to hold the Plunger, The Shift Lever, and the Drive Assembly Solenoid Switch Contacts in place to continue cranking the engine.

When the Ignition Switch is released from the START position, the battery voltage is removed from the Starter Solenoid and the junction of the two Windings. Voltage is applied from the Motor Contacts through both Windings to ground at the end of the Hold-In Winding. However, the voltage applied to the Pull-In Winding is now opposing the voltage applied when Winding was first energized. The magnetic fields of the Pull-In and Hold-In Windings now oppose one another. The Return Spring then causes the Drive Assembly to disengage and the Solenoid Switch Contacts to open simultaneously. As soon as the contacts open, the starter circuit is turned off.