Active Grille Air Shutter - If Equipped

During normal driving operation, the PCM determines the active grille vane position. This is 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 (ECT)
A/C demand
The ambient air temperature
The fuel temperature.

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 motor loses its memory. Therefore a calibration is required every time when the vehicle is in Power Mode 6 (Ignition ON). Except if the PCM has remained active between ignition OFF and the vehicle is in Power Mode 6 (Ignition ON), for example electric cooling fan after-run.

NOTE: The active grille air shutter vane motor is very sensitive to voltage drops from the Power Mode 9 (Engine cranking) and may trigger a further calibration.

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' 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.

Fault Diagnostics

If there is a fault with the active grille air shutter, the 'Engine Over Temperature' warning is displayed in the 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 in built temperature threshold.
Disconnect fault - Linkage between the motor and the vanes becomes disconnected.
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.