Operation

The Air Suspension Electronic Control Module performs two functions. It maintains vehicle height at a preset level (trim), and it switches automatically between soft ride and firm ride. Soft ride occurs during normal driving conditions; firm ride occurs during hard braking, acceleration, or cornering to improve vehicle handling.

Vehicle Height

To control vehicle height, the Air Suspension Electronic Control Module receives inputs from three height sensors. To maintain vehicle height the Module controls four air springs, four Air Spring Vent Solenoids, an Air Suspension Compressor Motor, a Vent Solenoid, and a Compressor Relay.

To raise the vehicle, the Module first turns on the comparessor through the compressor relay. After a one second delay, the desired Air Spring Solenoid is turned on. This condition is maintained until the Module determines, through the Height Sensors, that the vehicle has reached the desires (trim) level. The Compressor Relay and the Air Spring Solenoid are then turned off.

Lowering the vehicle is done in much the same way, except the Vent Solenoid is turned on instead of the compressor Relay, ignoring the one second delay.

Air Suspension Switch


The Air Suspension Switch operates the System during repair and/or diagnostic procedures.

The Air Suspension System works for up to one hour after the Ignition Switch is turned off. During this time, the Vent Solenoid Will be operated as often as required. However, the Compressor Motor operates only once.

Programmed Ride Control

The Programmed Ride Control opeates automatically when the Ignition Switch is in RUN. The ride control is enabled when battery voltage is applied through Fuse 5 to the Air Suspension Electronic Control Module. Under normal driving conditions, the Module momentarily energizes the Soft Shock Relay, which applies voltage to four Shock Actuators, rotateing them to the soft ride setting.

Air Suspension Electronic Control Module

The Air Suspension Electronic control Module receives inputs from the Steering Rate Sensor, the Electronic Engine Control Module, Brake Pressure Switch and Shock Actuator position inputs. The Module uses these inputs to determine when the vehicle should be set for firm ride.

During quick turns, wide open throttle or heavy braking, the Module momentarily energizes the Hard Shock Relay. This applies battery voltage to the Shock Actuator's other inputs, which rotates them to the hard setting.

When the Module senses that the vehicle has returned to normal cruise, the Soft Shock Relay is momentarily energized again to return the Shock Actuators to their soft ride setting.