System Operation

Active Grille Shutter System

System Operation

System Diagram





Network Message Chart

PCM (Powertrain Control Module) Network Input Messages





Grille Shutter

The grille shutter actuator positions the grille shutters based on commands from the PCM (Powertrain Control Module). The grille shutter moves 90 degrees from fully closed to fully open and, based on the position commanded by the PCM (Powertrain Control Module), is set in 1 of 16 positions (approximately 6 degrees between positions).

During normal operation, the grille shutter fully opens when the engine is off. Once the engine is started, a calibration of the grille shutter system occurs, which typically takes 15-20 seconds. The grille shutter system performs the calibration sequence by detecting the end positions, open and closed. The calibration sequence can begin in either direction, open or closed, and continues until it is successful or a fault is sensed. It is possible there can be a long pause between the 2 portions (open/close) of the calibration sequence. Calibration of the grille shutter system cannot be manually requested, it only occurs as determined by the grille shutter actuator. If certain faults are present (shutter blocked or actuator error), a recalibration is initiated in an attempt to resolve the problem. If the problem is not resolved after a calibrated number of attempts (usually 3 or 4), the fault timers time up and set a DTC (Diagnostic Trouble Code) when the timer reaches the limit. Other faults also trigger a recalibration request, but not until a grille shutter DTC (Diagnostic Trouble Code) is set in the PCM (Powertrain Control Module).

The PCM (Powertrain Control Module) communicates the desired position (open or closed) of the grille shutter based on various PCM (Powertrain Control Module) inputs (vehicle speed, coolant temperature, ambient temperature, A/C (Air Conditioning) system pressure, etc.). The PCM (Powertrain Control Module) communicates to the grille shutter actuator via a LIN (Local Interconnect Network). The LIN (Local Interconnect Network) supports bi-directional communication between the grille shutter actuator and PCM (Powertrain Control Module), allowing the grille shutter actuator to communicate position and fault information to the PCM (Powertrain Control Module).

The PCM (Powertrain Control Module) reports grille shutter DTCs (Diagnostic Trouble Codes) when the fault information is communicated by the grille shutter actuator for a predetermined amount of time. Any failures of the LIN (Local Interconnect Network) for over 10 seconds continuously results in the grille shutter actuator positioning the grille shutter fully open. There is no indication to the driver of the vehicle when a fault with the grilled shutter system is present or a grille shutter DTC (Diagnostic Trouble Code) is set in the PCM (Powertrain Control Module).