Suspension Control ( Automatic - Electronic ): Testing and Inspection

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 J 1962 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
The accelerometers have the following characteristics. At 0 g (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.

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 following fuses:
- Engine compartment fuse box, fuse F5 (10A).
- Engine management fuse box, fuse F1 (20A).

Check the following ADCM input/output lines:
- System error output from the ADCM to the instrument cluster.
- Vehicle speed output from the instrument cluster to the ADCM.
- Footbrake signal to the ADCM.

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 or socket.