Suspension Control ( Automatic - Electronic ): Description and Operation

Adaptive Damping System






Description
The Adaptive Damping System available as an option, matches damping effect with vehicle driving forces, to provide optimum ride and handling performance.
The system which is completely automatic and requires no drive input, comprises the following components:
Four adaptive damping units installed in the normal shock absorber positions. These are identified by a harness connector incorporated in the top of each unit.
An Adaptive Damping Control Module (ADCM) installed in the trunk adjacent to the battery.
Two vertical movement sensors (accelerometers), one installed on the bulkhead below the air conditioning unit, the other in the trunk below the fuel tank.
A lateral movement sensor (accelerometer) installed within the RH side false bulkhead.

Operation
The four adaptive damping units are simultaneously switched to either firm or soft setting to suit circumstances. When the vehicle is stationary, the system adopts the firm setting to minimize vehicle pitch during initial acceleration. From 8 km/h (5 mph) upwards, the system reverts to the soft setting until otherwise switched by the ADCM.
On detecting cornering forces, the lateral sensor transits signals to the ADCM, which in turn switches the damping units to the firm setting, reducing vehicle roll-rate and improving wheel control.
On detection of a bump or depression in the road, the vertical sensors transmit signals to the ADCM, which in turn switches the damping units to the firm setting to minimize vehicle body movement.
Under braking conditions, the ACDM, on receipt of a signal, commences calculation of vehicle deceleration. When deceleration exceeds a predetermined threshold, the ADCM switches the damping units to the firm setting, reducing vehicle pitch rate and improving wheel control.
Following completion of a cornering maneuver, negotiation of road surface undulations, or heavy braking, that has necessitated switching to the firm setting, the ADCM always returns the damping units to the soft setting.
In the event of failure of the Adaptive Damping System, the damping units automatically revert to the Firm setting, ensuring that the vehicle remains safe to drive under all circumstances. The driver will be alerted to such a failure by illumination of a "SUSPENSION FAULT" warning on the fascia message center and the amber warning light in the instrument cluster.






ADCM/Component Relationship
Three accelerometers sense vehicle body movement and generate an analog voltage (+5V max.) output, which is proportional to the vehicle body movement. These voltages are supplied to the Adaptive Damping Control Module (ADCM).
At Og. (no movement of the body) each vertical accelerometer outputs approximately 2.5V steady voltage. The lateral accelerometer outputs approximately 1.5V. The voltage output due to body movement is proportional to acceleration in the acceleration axis, up to approximately 4.5V and down to approximately 0.5V.
The ADCM is hardwired to the Instrument Cluster. Should a fault occur, the ADCM grounds the System Error line which switches on the amber warning lamp and displays the message SUSPENSION FAILURE on the message center.

Refer to PDU User Guide
Refer to the PDU User Guide for details of diagnosing and testing the Adaptive Damping System. The PDU interrogates the ADCM directly via the K and L lines to the diagnostic socket.
The PDU will give an indication of the integrity of each electronic and electrical component. It will indicate, for example, that the accelerometers are not broken, but not that they functioning correctly when the vehicle is in motion. However, it is exceptional for an accelerometer to function incorrectly in its dynamic mode if it is proved to be functioning when static.

Basic Checks
Before changing any component, refer to the circuit diagrams and check the continuity of relevant harness circuits; in some instances, the PDU will not differentiate between a faulty component and a damaged connection or wiring.
Check the System Error line from the ADCM to the Instrument Cluster - Fascia Harness pin FC025/006. Check the Road Speed Output from the Instrument Cluster to the ADCM - Fascia Harness pin FC026/007.
Check any relevant connections to confirm that the connection is electrically sound and that a terminal pin has not been pushed back into the connector shell, ie. not making a connection to its mating pin/socket.
Check the following fuses in the luggage compartment fusebox: Fuse No. 2 (20A) and Fuse No. 4 (5A).








Connector Pin Identity Chart for BT069