GM Service Manual Online
For 1990-2009 cars only

The starter motor features small permanent magnets mounted inside the field frame and a planetary gear reduction mechanism between the armature and drive. A permanent magnet gear reduction motor is about half the weight and size of a field coil motor having the same cranking performance. The drive housing encloses the shift lever, the shift lever mechanism, and the solenoid plunger to protect them from exposure to dirt, icing conditions, and splash.

The theft deterrent relay is energized by the instrument cluster via CKT 625 (YEL/BLK). The theft deterrent relay provides battery voltage to the starter solenoid contacts. This applied voltage energizes the solenoid windings and causes movement of the solenoid plunger and shift lever, causing the drive pinion to engage the engine flywheel ring gear and close the solenoid switch contacts. When the solenoid switch contacts close, the starter motor energizes and cranking takes place. As the engine starts, the pinion overrun clutch protects the starter armature from excessive speed until the ignition switch is opened. Once the solenoid windings are de-energized, the return spring causes the pinion to disengage.