Air Suspension System Operation
- The suspension adjusts if the vehicle's doors are open, but the vehicle may not lower to its minimum setting.
- A time delay may be evident before the vehicle reacts to a suspension height request, via the switches. The vehicle's systems need to be configured before each height adjustment.
Under normal operating conditions, the Chassis Control Module (CHCM) keeps the vehicle level at the current ride height. The incoming height signals from the sensors are passed through filters to remove irregular signals produced by road noise or other irregularities. When the vehicle is stationary or a height change is in progress, the signals are passed through a fast filter. The fast filter tracks the true rate of change of height. When the vehicle is moving, the signals are passed through a slow filter. The slow filtered signals remove almost all road noise from the signals and output a true long term average for each corner height. The slow filtered signals cannot be used to respond quickly during height changes.
The CHCM monitors each corner height signal using the fast filtered signals if the vehicle is stationary or the slow filtered signals if the vehicle is moving. If the height remains in a dead band which is ±9 mm from the target height, the control module does not implement any height adjustment changes. When the CHCM detects that a corner is outside of the 'dead band', the CHCM operates the compressor and/or the valves to move that corner back into the target height.