Speed Sensitive Suspension (SSS)

Fig. 1 Damping Mode To Speed Input Comparison.:

DESCRIPTION
The Speed-Sensitive Suspension system controls the firmness of the car's ride by automatically controlling an actuator in each of the four struts. The system has three damping modes; comfort, normal and firm. The control module determines damping mode selection according to vehicle speed conditions, lift/dive input, lateral acceleration switch input and any error conditions which may exist. When two demanded positions conflict, the system will go to the firmest damping position.

The control module located on the right electronics bay in the luggage compartment controls and monitors the speed-sensitive suspension system. The control module also controls the Speed-Sensitive Steering system. The control module receives speed, lift/dive and lateral acceleration input and determines the optimum mode strut valving for current operating conditions. The control module also receives feedback from the struts to determine proper system operation. If the control module receive an incorrect feedback signal for two successive ignition cycles, an error code will be set in memory and a SERVICE RIDE CONTROL message will be displayed on the driver information center.

Each strut contains an electrical actuator which rotates a selector valve to a specific location commanded by the control module. The selector valve contains different size orifices which will increase or decrease the damping rate of the strut to control ride firmness. The actuators are an integral part of the strut and cannot be serviced separately. To determine which damping mode the system should be in based on speed input, refer to Fig. 1.

Lift/dive input is received from the Powertrain Control Module (PCM). The system will go to the firm mode during wide open throttle to provide anti-lift. The system will go to the firm mode when there is a high deceleration rate to provide anti-dive.

The lateral acceleration switch (accelerometer) provides the control module with body roll information. The control module will command the struts to the firm mode when the switch senses lateral acceleration.

Each actuator provides a feedback voltage signifying the actuator position relative to a Home position. A single 3-volt pad signifies the home position which correlates to the first comfort damping position of the actuator, while subsequent zero to 1-volt pads signify the remaining damping positions. Each damping position is separated by a 5-volt pad.