Electronic Suspension Control Description and Operation HSV

Important:  Magnetic Ride Control is referred to as Electronic Suspension Control within the service documentation.

The Electronic Suspension Control system, also known as the Magneto - Rheological Real Time Damping (MRRTD) system independently controls the fluid viscosity in each of the front and rear struts in order to control the vehicle ride characteristics. The ESC system is capable of making these changes within milliseconds. The ESC system consists of the following major components:

The ESC controls the damping mode selection according to the following factors:

The ESC module evaluates these inputs in order to separately control the shock absorbers, providing an enhanced ride and comfort level over the widest possible range of operating conditions.

The ESC module provides electronic control logic and output drive for each front and strut and rear damper. The ESC module makes decisions due to road and driving conditions based on various inputs. The ESC module receives input information by sensors that are directly connected to the ESC module or by other systems through the serial data line.

The ESC module uses these inputs in order to independently control the struts or dampers at each corner of the vehicle. The ESC module is located behind the front right close out panel.

The ESC switch is a raises or lowers the electronic current passing through the electronic shock absorbers on the front and rear of the vehicle to enhance the ride and handling of the vehicle. The ESC switch is a momentary switch, meaning it is activated by a single depression of the switch, after which it returns to its static position. The ESC switch is contains an LED to indicate when the ESC System is engaged in the intensified setting.

The ESC position sensors provide the ESC module with the body to wheel displacement input. The ESC module uses this and other inputs in order to control the stiffness of the front struts and rear dampers. If any body or wheel motion is detected, the ESC module will determine how soft or firm each strut / damper should be to provide the best ride. The ESC position sensors are mounted at each corner of the vehicle between the control arm and the body.

The ESC struts are of a monotube design that which provide damping by increasing magnetic flux to magnetic particles to resist suspension movement. The ESC struts have the capability of providing multiple modes or values of damping forces, in both compression and rebound direction. The damping forces are achieved by increasing or decreasing the magnetic flux to the shock absorbers.

The front ESC actuator connector is located at the bottom of the struts. The rear ESC actuator connector is at the top of the strut. The rear struts have jumper harnesses for ease of maintenance.

The ESC system uses the information from other systems in order to execute certain functions.

The ESC system has a malfunction indicator lamp. When the ESC system detects a malfunction that sets a DTC, the ESC system sends a message on the serial data line directly or through the PCM to the I/P mounted Malfunction Indicator Lamp , which illuminates.

The MIL will only be displayed if the ESC system detects a malfunction that sets a DTC and causes the ESC system to disable all four shock absorbers. The ESC system will send a message on the serial data line to the IPC to display this message.

The SERVICE RIDE CONTROL message will only be displayed if the ESC system detects any malfunction that sets a DTC. The ESC system will send a message on the serial data line to the IPC to display this message.

The MAXIMUM SPEED message will only be displayed if the ESC system detects a malfunction that sets a DTC and causes the ESC system to disable all four shock absorbers. The ESC system will send a message on the serial data line to the PCM indicating that all four shock absorbers were disabled. The PCM then sends a message to the IPC to display this message. The vehicle speed will be limited to 125 Km/H when a fault is detected.

The ESC module has the ability to store diagnostic trouble codes (DTC's) as current or history codes. Most ESC system malfunctions will display a message in the IPC and set a DTC. The message will remain ON until the RESET button is pressed on the Driver Information Center (DIC). As long as the DTC is current, the message will be displayed after every ignition cycle and the RESET button must be pressed to bypass the message.

The ESC system uses an ignition cycling diagnostic approach in order to reduce the occurrence of false or intermittent DTC's that do not affect the functionality of the ESC system. This allows for the fail-soft actions to be taken whenever a malfunction condition is current, but requires the malfunction to be current for a certain number of ignition cycles before the corresponding malfunction code and message will be stored or displayed.

If the ESC detects a malfunction, the ESC system defaults with a fail-soft action. A fail-soft action refers to any specific action the ESC system takes in order to compensate for a detected malfunction. A typical ESC fail-soft action would be if the ESC system detects a malfunction with a shock absorber, the ESC system will ignore this input and fail-soft to the TOUR ride setting.

It is possible for a suspension position sensor to become stuck. This fault would not be detected by the ESC module, therefore a DTC would not be set and no message would be displayed by the IPC. This fault is addressed under Symptoms - Electronic Suspension Control.