A scan tool must be used in diagnosing system malfunctions before removing or replacing any of the components. Become familiar with the scan tool diagnostic capabilities and thoroughly understand each of the diagnostic features described before attempting any diagnostic procedures. The scan tool is capable of displaying data and input/output information from all of the systems connected to the serial data line. The scan tool is also capable of commanding the shock absorbers ON or OFF without the need for any input information.

The scan tool's data display function can be helpful in determining if the RTD system is operating properly and reading the correct data from a particular component.

An example of the use of the scan tool data display functions to diagnose a VSS malfunction might involve the PCM data display. For example, the RTD system stores a DTC C1743 (Loss of Vehicle Speed Signal). In order to diagnose this condition using the scan tool, select the PCM's data display function. Then, check if the PCM is receiving and interpreting the proper VSS data from the sensor. If the PCM is not reading the proper VSS data, the RTD system is not the problem. The PCM must be further diagnosed.

If the PCM is receiving and interpreting the proper VSS data, then select the IPC data display function and check if the IPC is able to receive the VSS data from the PCM. If the PCM and the IPC are both able to receive this data. then carefully inspect where the RTD system receives this input.

The scan tool's input display function can be helpful in determining if the ESC module is receiving the correct input status. This can assist in determining if the RTD system is actually commanding a shock absorber. For example, the RTD system requires the input status from the ride control switch in order to determine the ride settings. A starting point might be to select the ride control switch input display function from the scan tool menu. The input status should change when the switch is manually operated. If no change occurred, then the problem is current and the input could be stuck. A shorted, open or malfunctioning switch or related wiring might cause the input to be stuck. If the change did occur, the problem is intermittent. In order to diagnose this condition using a scan tool, select the scan tool's input function. Then, watch the ride control switch input while moving the suspected wiring/connector. Try to duplicate the malfunction conditions. This scan tool feature allows checks that could not be performed while driving the vehicle.

A scan tool may be used in order to command the shock absorbers ON or OFF, without the need for input information from other components. This can be very helpful in determining if a certain portion of a circuit or a component is in working order.

Using a scan tool, select the RTD outputs functions from the scan tool menu. The status of the output being cycled will be shown on the scan tool's display screen. The shock absorbers can be cycled to turn ON or OFF using the scan tool output control function.

Using the LF shock absorber as an example, commanding the LF shock absorber ON can indicate whether the RTD system is able to correctly operate the LF shock absorber. This can determine if a DTC that pertains to that shock absorber is able to reset, and if the ESC module's internal circuitry is able to operate the LF shock absorber. For example, suppose the RTD system sets an intermittent DTC C1711 (LF Shock Absorber Solenoid Short to Ground). In order to diagnose this condition using a scan tool, select the RTD output function. Then, cycle the LF damper while moving the suspected wiring/connector. Attempt to duplicate the malfunction conditions. This scan tool feature allows checks that could not be performed while driving the vehicle. This example can be applied to the other shock absorbers.