System Diagnostics

Fault detection is through active and stored Diagnostic Trouble Codes (DTCs)

• DTCs are displayed by the DRBIII®.
• Active DTCs are those which currently exist in the system. The condition causing the fault must be repaired in order to clear this type of DTC.
• Stored DTCs are those which occurred in the system since the A/C-Heater Control Module received the last "clear diagnostic info" message.

The A/C Cooldown Test:

• is actuated with the DRBIII®.
• checks A/C system performance based on evaporator temperature sensor input.
• will not run if ambient temperature is below 12.7°C (55°F).
• will pass if the evaporator temperature drops 6.7°C (20°F) within two minutes of starting the test.
• faults display on the DRBIII® as test messages only after running the test.
• faults will not display on the DRBIII® as Diagnostic Trouble Codes.
• for RS vehicles will cause the Rear Wipe/Wash and A/C status indicators on the A/C-Heater Control Module to flash alternately while the test is running.
• for RG (Export) vehicles will cause the PWR and A/C status indicators on the A/C - Heater Control Module to flash alternately while the test is running.
  • The A/C status indicator will flash twice per second to indicate that the A/C Cooldown Test needs to be run. The A/C status indicator will stop flashing twice per second if either the A/C Cooldown Test returns passed, or if any button on the control is pressed, or if the ignition is cycled and the odometer shows greater than eight miles.

The HVAC Door Recalibration function:

• is actuated with the DRBIII®.
  • After completing HVAC Door Recalibration, the DRBIII® will the store the total span and the status of each door actuator. Selecting HVAC Door Cal Monitor in the System Tests will display this information.
• homes and repositions door actuators.
• monitors for door span faults on the actuator circuits.
• faults display on the DRBIII® as test messages only after running the test.
• faults will not display on the DRBIII® as Diagnostic Trouble Codes.
• for RS vehicles will cause the Rear Wipe/Wash and RECIRC status indicators on the A/C-Heater Control Module to flash alternately while the test is running.
• for RG (Export) vehicles will cause the PWR and RECIRC status indicators on the A/C - Heater Control Module to flash alternately while the test is running.
  • The RECIRC status indicator will flash twice per second to indicate that the HVAC Door Recalibration Test needs to be run. The RECIRC status indicator will stop flashing twice per second if either the HVAC Door Recalibration Test returns passed, or if any button on the control is pressed, or if the ignition is cycled and the odometer shows greater than eight miles.

The Actuator Circuit Test:

• is actuated with the DRBIII®.
• monitors for shorted actuator circuits.
• allows service to easily diagnose and troubleshoot up to three simultaneous shorts.
• supplements the continuous diagnostics on the actuator drive system.
• faults display on the DRBIII® as test messages only after running the test.
• faults will not display on the DRBIII® as Diagnostic Trouble Codes.

When Performing the Actuator Circuit Test