System Description

Based on a signal transmitted from each sensor, ECM calculates a target fan speed responsive to a driving condition. In addition, ECM calculates a fan pulley speed according to an engine speed and transmits a cooling fan request signal to IPDM E/R via the CAN communication line to satisfy the target fan speed. Then, IPDM E/R transmits ON/OFF pulse duty signal to electrically-controlled cooling fan coupling.
The cooling fan speed sensor detects a cooling fan speed and transmits the detection result to ECM.
ECM judges the start signal state from the engine speed signal and battery voltage.