6. Starting System

When the ignition key is in the START position, a solenoid switch engages the starter's drive pinion with the ring gear on the engine flywheel or drive plate. To minimize wear and stress on the drive pinion and ring gear, the solenoid does not switch current to the starter until the drive pinion is fully engaged. Also, the drive pinion has an overrunning clutch to prevent the starter from being driven by the engine.

Cars with passive restraint seat belts have a starting interlock feature that prevents the starter from being actuated if the belts are unfastened. Power from terminal 50 of the ignition switch goes first to the starter interlock relay, and then from the relay to the starter. The relay is controlled by the seat belt warning control unit. If the belts are unfastened when the ignition key is turned, the relay remains open and interrupts power to the starter.