Ignition Switch ON (Engine Off) Mode
When the ignition switch activates the fuel injection system:1. The PCM determines atmospheric air pressure from the MAP sensor input to determine basic fuel strategy.
2. The PCM monitors the engine coolant temperature sensor and throttle position sensor input.
- The PCM modifies fuel strategy based on this input.
When the key is in the ON position and the engine is not running (zero rpm):
The auto shutdown relay and the fuel pump relay are not energized.
- Therefore, voltage is not supplied to the fuel pump, ignition coil, fuel injectors or heated oxygen sensors.