Starting System: Description and Operation

Voltage is present at the Ignition Switch contacts at all time. Voltage is present at the Starter Relay and Starter Motor/Solenoid contacts at all times.

With the Ignition Switch in START and the Backup/Neutral Safety Switch contacts closed, current flows through the Ignition Switch, the Backup/Neutral Safety Switch and the Starter Relay to ground. The Starter Relay coil is energized and its contacts close.

Current now flows from the Battery to the Starter Motor/Solenoid pull-in and hold coils, and both coils are energized. The starter drive gear is pushed forward to mesh with the engine flywheel and, at the same time, the Starter Motor/Solenoid contacts close.

Current flows from the Battery to the Starter Motor to crank the engine. As soon as the Starter Motor/Solenoid contacts close, voltage is present at both ends of the Starter Motor/Solenoid pull-in coil and the coil de-energizes. The hold coil remains energized and is powerful enough to keep the starter driver gear in contact with the engine flywheel.

The Electronic Engine Control System uses some of the Starting System circuitry to determine whether or not the transmission is in gear (NDS input).

With the Backup/Neutral Safety Switch in "P" or "N," pin 30 of the Electronic Engine Control (EEC) Module is grounded through circuits 32 (R/LB), 33 (W/PK), the Starter Relay coil and the Backup/Neutral Safety Switch.