Function Sequence For Dynamic Idle Speed Control

Dynamic idle speed control sets the engine's idle speed such that no current needs to be drawn from the battery when the vehicle is idling. The idle speed is increased for a higher consumer load. Idle speed increase is done in a preventive manner. The system adopts the required idle speed based on the present load.

The following factors are used for dynamic idle speed control computations:

• Alternator excitation current
• Alternator operating rate
• Battery voltage
• Battery current
• Engine speed
• Consumer reduction shutoff stage
• State of battery
• Engine start

The maximum possible excitation current is calculated from the current excitation current and the alternator utilization.

The maximum possible excitation current is used to calculate the maximum possible alternator current at different idle speeds.

EMCM transmits corresponding requests via CAN communication to ECM, which then raises the idle speed accordingly.

The idle speed is reversed under the following circumstances:

• Consumer load no longer high