Ignition Switch On (Zero RPM) Mode

When ignition switch activates fuel injection system, the following actions occur:

• The PCM monitors engine coolant temperature sensor and throttle position sensor input. The PCM determines basic fuel injector pulse width from this input.
• The PCM determines atmospheric air pressure from MAP sensor input to modify injector pulse width.

When key is in ON position and engine is not running (zero RPM), Auto Shutdown (ASD) and fuel pump relays de-energize after approximately 1 second. Therefore, battery voltage is not supplied to fuel pump, ignition coil, fuel injectors and heated oxygen sensors.