Active Grille Air Shutter

WARNING: This page is about a different variant/trim than selected.

Normal driving operation

The Powertrain Control Module (PCM) determines the active grille vane position from the thermal condition of the vehicle, which is an output of the fan control logic.

The vane position depends on the following:

The engine coolant temperature
The Air Conditioning (A/C) demand
The ambient air temperature
The fuel temperature
The Terrain Response mode selection.

If vehicle speed reaches 180 km/h (112 mph) the vanes move to the fully open position. The vanes resume a calculated opening position when vehicle speed decreases to 140 km/h (87 mph).

If the electric cooling fan continue to operate after the engine stop (after-run), the vanes remain open. When the electric cooling fan stops, the vanes close and the motor send a signal to the PCM indicating that is ready to power down.

Calibration mode

When the PCM shuts down, the active grille vane motor loses its memory. Therefore a calibration is required, when the ignition is switched ON. Except if the PCM has remained active between ignition OFF and ignition ON, for example electric cooling fan after-run.

Calibration only commences after the engine has started.

The calibration process opens and closes the vanes to find the end stops and range of motion between them. This range of movement is checked and if the range is within the specified limits, the cycle is passed. This cycle can take up to 16 seconds.

The calibration cycle is a total of 6 open/close attempts. If the first attempt fails, as soon as a position demand exceeds 45%, the software completes the 5 remaining attempts. These continue 1 after the other, until they either pass a calibration or fail all 6 attempts.

A 'Calibration Failed Fault' Diagnostic Trouble Code (DTC) is only be stored if the calibration fails from the first attempt and all attempts are completed. The vanes are to be commanded to open as much as possible. If the first calibration passes, then a 'Calibration Failed Fault' DTC cannot be set until the next drive.

NOTE: The active grille air shutter vane motor is very sensitive to voltage drops from engine cranking and may trigger a further calibration.

Jet Wash Mode

Jet wash mode allows the motor to fully open the vanes and then power down so that the radiator can be cleaned.

To activate jet wash mode:

Start and run the engine.
Stop the engine and set the ignition OFF.
Set the ignition to ON.
Select Terrain Response (TR) sand mode.
Set the ignition to OFF.

This sequence prevents to enter jet wash mode accidentally when the ignition is switched OFF in sand mode.

The vanes are default to be fully open even the calibration is completed or not. (See calibration mode section above)

When the position feedback shows that the vanes are fully open, the motor indicates to the PCM that it is ready to power down.

Diagnostics

If there is a fault with the active grille air shutter, the 'Engine Over Temperature' warning is displayed in the Instrument Panel Cluster (IPC). For each fault, a flag is set and after a calibrated de-bounce time, a DTC is stored in the PCM.

The following faults can be detected:

Mechanical blockage fault - Motor encounters too much resistance and stalls. Max torque = 0.7 - 0.8 Nm (6.2 - 7 lbin). If blocked, the motor try to re-calibrate up to maximum number of attempts as described in the calibration section.
Calibration failed fault - Fault stored if all calibration attempts have failed in that drive cycle.
Electrical fault - Motor reports an internal electrical fault.
Supply voltage fault - Motor supply voltage falls outside the range 7.5V - 17.5V.
Thermal shutdown fault - Motor circuits exceed their inbuilt temperature threshold.
Disconnect fault - Linkage between the motor and the vanes becomes disconnected.
Local Interconnect Network (LIN) bus communication fault and Node detection fault
- A fault with the active grille vane motor, its signal wire or its supply that causes a breakdown in signals to the PCM.

If the motor is still operational and only the signal wire has a short circuit/open circuit:

After 10 seconds of not receiving a signal, the active grille vane motor turns the vanes fully open.