Active Grille Shutter

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

During normal operation, the grille shutter may be partially to fully open when the engine is off, depending on the ambient temperature. When 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. A long pause may occur 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), a timer starts and sets a DTC  when the timer reaches a predetermined limit. Other faults also trigger a recalibration request, but not until a grille shutter DTC  is set in the PCM  .

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

The PCM  sets grille shutter Diagnostic Trouble Codes (DTCs) when the fault information is communicated by the grille shutter actuator for a predetermined amount of time. Any failures of the LIN  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 grille shutter system is present or a grille shutter DTC  is set in the PCM  .