Road Sensing Suspension Description and Operation

Road Sensing Suspension Description and Operation

The Electronic Suspension Control (ESC) system consists of the following components:
^ Electronic Suspension Control (ESC) module (3)
^ Four dampers contained in the two front struts (5 and 6) and the two rear shock absorbers (1 and 9)
^ Four positions sensors (2, 4, 7, and 8)
^ ALC air compressor module (10)
^ Damper relay (not shown)
^ ELC relay (not shown)
The Electronic Suspension Control (ESC) system with rear Automatic Level Control (ALC) controls damping forces in the front struts and rear shock absorbers in response to various road and driving conditions. The rear ALC portion of the system maintains a proper vehicle trim height under various vehicle load conditions.

NOTE: The Electronic Suspension Control (ESC) module will remain powered for a short period of time (typically under 5 minutes) after the ignition has been turned off. This system-on period after ignition-off allows the system to level and perform other required functions.
The Electronic Suspension Control (ESC) module receives the following inputs: wheel-to-body position, vehicle speed, and lift/dive. The Electronic Suspension Control module evaluates these inputs and controls actuators in each of the dampers independently to provide varied levels of suspension control.

Electronic Suspension Control (ESC) Module
The Electronic Suspension Control (ESC) module is used to control how firm or soft each shock or strut should be to provide the best ride. The control module is also used to control the vehicles rear height. The control module is located on the right side of the rear seat back and is accessed through the trunk.

Position Sensors
The position sensors are 0 to 5 volt DC output devices that are used to measure wheel-to-body movement/position. There are four position sensors on the vehicle, one per corner. Each position sensor is mounted between a suspension control arm and the body.

Shock Absorber or Strut
A CVRSS damper is mounted at each corner of the vehicle. The four suspension dampers (two front struts and two rear shock absorbers) each contain an integral solenoid actuator that is controlled by the Electronic Suspension Control (ELC) module. The solenoid actuator provides a wide range of damping forces between soft and firm levels. Damping is controlled by the amount of current supplied to the actuator.

Vehicle Speed
The Electronic Suspension Control module receives two (2) vehicle speed inputs. One input is received via a wire from the Powertrain Control Module (PCM). The other input is obtained over the CLASS 2 serial communication buss. Vehicle speed is used to determine the amount of damper control necessary.

Lift/Dive
Lift/Dive input is received from the PCM. When the Electronic Suspension Control module receives an active lift/dive input, it will command a firm damping level on all four corners. The lift signal is calculated in the PCM based on throttle position, transmission gear, vehicle speed, and brake switch status. The dive signal, also calculated in the PCM, is based upon the rate of change with the vehicle speed.