Principles Of Operation

The Integrated Suspension Control Module (ISCM) uses a combination of information from other system modules and data from the body vertical accelerometers and suspension height sensors to measure the vehicle and suspension states and driver inputs. Using this information, the ISCM applies algorithms to control the dampers for the current driving conditions.

The ISCM receives the following signals on the High Speed (HS) Controller Area Newtwork (CAN) chassis systems bus from the stated system components:

• Brake pressure - Anti-lock Brake System (ABS) control module.
• Brake pressure quality factor - ABS control module.
• Car configuration parameters - Central Junction Box (CJB).
• Engine speed - Engine Control Module (ECM).
• Engine speed quality factor - ECM.
• Engine torque flywheel actual - ECM.
• Engine torque flywheel actual quality factor - ECM.
• Gear position target - Transmission Control Module (TCM).
• Lateral acceleration - ABS control module.
• Power mode (ignition signal) - CJB.
• Power mode quality factor - CJB.
• Roll stability control mode - ABS control module.
• Steering wheel angle - ABS control module.
• Steering wheel angle speed - ABS control module.
• Steering wheel angle status - ABS control module.
• Terrain mode requested - Transmission Control Switch (TCS).
• Torque converter slip - TCM.
• Vehicle information parameters HS - CJB.
• Vehicle speed - ABS control module.
• Vehicle speed quality factor - ABS control module.
• Front left wheel speed - ABS control module.
• Front left wheel speed quality factor - ABS control module.
• Front right wheel speed - ABS control module.
• Front right wheel speed quality factor - ABS control module.
• Rear left wheel speed - ABS control module.
• Rear left wheel speed quality factor - ABS control module.
• Rear right wheel speed - ABS control module.
• Rear right wheel speed quality factor - ABS control module.

The ISCM also outputs information on the High Speed (HS) Controller Area Network (CAN) bus for use by other systems as follows:

• Fault message - Instrument cluster (IC).
• Terrain mode change status - TCS.
• Terrain mode - TCS.
• Front left suspension height - other systems as required.
• Front right suspension height - other systems as required.
• Rear left suspension height - other systems as required.
• Rear right suspension height - other systems as required.

The ISCM monitors the input signals and operates the damper solenoids. The input signals are used in control functions and a force required for each damper, for each function, is calculated. An arbitrator monitors the force requirements from each function and apportions a force to a damper. The force is converted to the appropriate current and sent to the damper.

The control functions are as follows:

• Body Control - Uses body vertical accelerometer and CAN inputs. Calculates road induced body motions 100 times a second and sets each damper to the appropriate level to maintain a flat and level body attitude. Provides improved body control without loss of ride quality.
• Roll Rate Control - Uses CAN inputs. Predicts vehicle roll rate due to driver steering inputs 100 times a second and increases damping to reduce roll rate. Provides improved control and driver confidence.
• Pitch Rate Control - Uses CAN inputs. Predicts vehicle pitch rate due to driver throttle and braking inputs 100 times a second and increases damping to reduce pitch rate. Provides improved control and driver confidence.
• Bump Rebound Control - Uses suspension height sensor and CAN inputs. Monitors the position of the wheel 500 times a second and increases the damping rate as the damper approaches the end of its travel. Provides improved ride quality.
• Wheel Hop Control - Uses suspension height sensor and CAN inputs. Monitors the position of the wheel 500 times a second and detects when the wheel is at its natural frequency and increases the damping. Provides improved ride quality.

Under normal road conditions when the vehicle is stationary with the engine running, the dampers are set to the firm condition to reduce power consumption.

The ISCM receives its power supply via a relay and fuse in the CJB. The relay remains energized for a period of time after the ignition is off. This allows the ISCM to record and store any Diagnostic Trouble Code (DTC) relating to adaptive dynamics system faults.