Starting System: Description and Operation

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

Vehicles Without Anti-Theft System

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

Current now flows from the Battery to energize the Starter Motor/Solenoid pull-in and hold coils. The Starter driver 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/Solenoid 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 is deenergized. The hold coil remains energized and is powerful enough to keep the starter drive gear in contact with the engine flywheel.

Vehicles Equipped With Anti-Theft System

Starting System operation for vehicles equipped with Anti-Theft is almost the same as for vehicles not so equipped. The difference is that the START signal from the Ignition Switch must pass through the Anti-Theft Controller Module. When the Anti-Theft System is triggered, the Anti-Theft Controller Module will not pass the START signal to the Starter Relay and the engine will not start.

All Vehicles

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 Lamp/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 Lamp/Neutral Safety Switch.