Affect of Road Undulation

The rear air suspension system is a microprocessor controlled active air suspension system. The microprocessor and support hardware are contained in the vehicle dynamics control module. The vehicle dynamics control module constantly determines the height position of the vehicle body relative to the vehicle wheels. The system maintains a predetermined trim height regardless of road conditions or vehicle passenger load. During normal operation, the vehicle dynamics control module uses a 45 second averaging interval for controlling vent and compress operations.
^ The 45-second averaging interval is used to keep the control module from making unneeded corrections.
^ When a vehicle at the correct trim height hits a bump, the air suspension height sensor output will read low and high in addition to trim until the oscillations die out.
^ If the control module were to correct for these "bump-induced" readings, system duty cycle would increase unnecessarily.
^ The 45-second averaging interval not only eliminates corrections due to bumps but also eliminates unnecessary corrections resulting from braking, accelerating and turning.
The control module tabulates the height sensor readings and does not begin a compress or vent operation until the air suspension height sensor reads low or high for 45 seconds continuously.