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.
Data Display
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.
Display Input Status
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.
Cycle Outputs
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 special 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 shock absorber solenoid 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.
Scan Tool Parameter | Data List | Units Displayed | Typical Data Value |
|---|---|---|---|
Turn the Ignition ON, Engine OFF//Vehicle Trim Height within Specifications | |||
GM Part Number | ID Information | Part Number | Varies |
GMSCM Software Version | ID Information | Version Number | Varies |
DSP Software Version ID | ID Information | Version Number | Varies |
EEPROM Calibration ID | ID Information | Calibration Number | Varies |
Right Front Position Sensor | Inputs | 0-5 Volts | 0.35-4.75 Volts |
Left Front Position Sensor | Inputs | 0-5 Volts | 0.35-4.75 Volts |
Right Rear Position Sensor | Inputs | 0-5 Volts | 0.35-4.75 Volts |
Left Rear Position Sensor | Inputs | 0-5 Volts | 0.35-4.75 Volts |
Steering Position PWM | Inputs | 0-10ms | Varies |
Vehicle Speed | Inputs | km/h (mph) | Varies |
Controller Battery Volts | Inputs | Volts | Battery Voltage |
Chassis Pitch Input Status | Inputs | Active/Inactive | Varies |
Chassis Pitch Input Change | Inputs | Change/No Change | Varies |
Ride Control Switch | Inputs | 0-5 Volts | 0.5-4.5 Volts |
Left Front Shock Absorber Solenoid | Outputs | 0-100% | 0-90% |
Right Front Shock Absorber Solenoid | Outputs | 0-100% | 0-90% |
Left Rear Shock Absorber Solenoid | Outputs | 0-100% | 0-90% |
Right Rear Shock Absorber Solenoid | Outputs | 0-100% | 0-90% |
RTD Scan Tool Data Definitions:
The RTD Scan Tool Data Definitions contains a brief description of all RTD related parameters available on the scan tool.
GM Part Number:: The scan tool displays the controller part number for service identification.GMSCM Software Version:: The scan tool displays the controller GMSCM software version number for service identification.
DSP Software Version:: The scan tool displays the controller DSP software version number for service identification.
EEPROM Calibration ID:: The scan tool displays the controller EEPROM calibration ID number for service identification.
Right Front Position Sensor:: The scan tool displays 0-5.0 volts. The position sensor is a variable resistor which changes with vehicle trim height. The RTD system uses this voltage reading to determine different road and driving conditions. The RTD system adjusts the damping level in each shock absorber based upon the voltage level received back from all four position sensors.
Left Front Position Sensor:: The scan tool displays 0-5.0 volts. The position sensor is a variable resistor which changes with vehicle trim height. The RTD system uses this voltage reading to determine different road and driving conditions. The RTD system adjusts the damping level in each shock absorber based upon the voltage level received back from all four position sensors.
Right Rear Position Sensor:: The scan tool displays 0-5.0 volts. The position sensor is a variable resistor which changes with vehicle trim height. The RTD system uses this voltage reading to determine different road and driving conditions. The RTD system adjusts the damping level in each shock absorber based upon the voltage level received back from all four position sensors.
Left Rear Position Sensor:: The scan tool displays 0-5.0 volts. The position sensor is a variable resistor which changes with vehicle trim height. The RTD system uses this voltage reading to determine different road and driving conditions. The RTD system adjusts the damping level in each shock absorber based upon the voltage level received back from all four position sensors.
Steering Position PWM:: The scan tool displays 0-10 ms. This PWM signal is sent by the ABS system which changes when the steering wheel is turned. The RTD system uses this PWM signal to determine the shock absorber control levels and will command a more firm setting if the vehicle is turning.
Vehicle Speed:: The scan tool displays 0-255 km/h (0-159 mph). The RTD system obtains vehicle speed data from the PCM on a dedicated input. The PCM is responsible for calculating correct vehicle speed data.
Controller Battery Volts:: The scan tool displays 0-26.0 volts. The battery voltage represents the system voltage measured at the controller battery input.
Chassis Pitch Status:: The scan tool displays Active or Inactive. The RTD system receives chassis pitch input from the PCM. The scan tool will display Active when the RTD system detects a change in chassis pitch status. When there is no change in chassis pitch, the scan tool will display Inactive.
Chassis Pitch Input Change:: The scan tool displays Changed or Unchanged. The RTD system receives chassis pitch input from the PCM. When there is a change in chassis pitch status , the scan tool will display Changed. If there is not change, the scan tool will display Unchanged.
Driver Select Switch:: The scan tool displays 0-5.0 volts. The ride control switch voltage level represents the position of the ride control switch. The ride control switch affects the resistance level of the switch circuit which changes the voltage level display by the scan tool. The scan tool will display the voltage ranges in the following switch positions: PERF 0.5-1.5 V, SPORT 0.5-2.5 V , and TOUR 2.5-3.5 V.
Left Front Shock Absorber Solenoid:: The scan tool displays 0-100%. This percentage represents the commanded state of the shock absorbers. When the RTD system commands the shock absorbers ON, the percentage will increase. When the RTD system commands the shock absorbers OFF, the percentage will decrease.
Right Front Shock Absorber Solenoid:: The scan tool displays 0-100%. This percentage represents the commanded state of the shock absorbers. When the RTD system commands the shock absorbers ON, the percentage will increase. When the RTD system commands the shock absorbers OFF, the percentage will decrease.
Left Rear Shock Absorber Solenoid:: The scan tool displays 0-100%. This percentage represents the commanded state of the shock absorbers. When the RTD system commands the shock absorbers ON, the percentage will increase. When the RTD system commands the shock absorbers OFF, the percentage will decrease.
Right Rear Shock Absorber Solenoid:: The scan tool displays 0-100%. This percentage represents the commanded state of the shock absorbers. When the RTD system commands the shock absorbers ON, the percentage will increase. When the RTD system commands the shock absorbers OFF, the percentage will decrease.
