GM Service Manual Online
For 1990-2009 cars only

Battery voltage is available at all times thorough Maxi-Fuse located in the underhood fuse-relay center. Voltage is made available at the ignition switch through CKT 740 (RED). When the ignition switch is placed in START, contacts in the switch close to apply voltage to CKT 5 (YEL). CKT 5 (YEL) terminates at PIN C of the clutch start switch for manual transmission or at PIN E of the park/neutral position switch for automatic transmission.

If the clutch pedal is depressed for manual transmission of if the automatic transmission is in the PARK or NEUTRAL position, contacts are closed which applies voltage to CKT 1035 (PPL/WHT) at PIN D of the clutch start switch or at PIN G of the park/neutral position switch. CKT 1035 (PPL/WHT) applies voltage to PIN 85 of the starter relay located in the underhood fuse-relay center. The starter relay coil is connected to PIN 85 and to PIN 86. CKT 150 (BLK) from PIN 86 provides a ground path to ground G102 and the starter relay coil is energized.

When the relay coil is energized, the contacts are closed to apply battery voltage to the starter solenoid via CKT 6 (PPL) to the starter solenoid terminal S. This provides voltage to the hold-in winding and the pull-in winding of the solenoid.

The circuit thorough the pull-in winding is completed to ground through the starter motor. The windings work together magnetically to pull in and hold in the plunger. The plunger moves the shift lever. This action causes the starter drive assembly to rotate as it engages 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 supplied directly to the starter motor and it cranks the engine.

As soon as the solenoid switch contacts close, voltage is no longer supplied through the pull-in windings, since battery voltage is supplied to both ends of the windings. The hold-in winding remains energized, and its magnetic field is strong enough to hold the plunger, shift lever and drive assembly solenoid switch contacts in place to continue cranking the engine.

When the ignition switch is released from the START position, battery voltage is removed from CKT 6 (PPL) and the junction of the two windings. Voltage is supplied from the motor contacts through both windings to ground at the end of the hold-in windings. However, the voltage supplied to the pull-in winding is now opposing the voltage supplied when the winding was first energized. The magnetic fields of the pull-in and hold-in windings now help the return spring, causes the starter drive assembly to disengage and solenoid switch contacts to open simultaneously. As soon as the contacts open, the starter circuit is turned off.