Normally, battery voltage fluctuates from 11.5V to 14.5V. Especially at cranking, voltage can drop to 9.8V. Therefore, actuators which require 12V power supply meet fluctuation of power by 5V.

A little change of voltage supply can shift controlling characteristic of actuators, such as injectors, Rail pressure regulator valve and EGR actuator, which should be controlled delicately. To correct controlling characteristic change arrised from voltage fluctuation, ECM performs actuator operating correction according to voltage change as detecting battery voltage change.