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 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 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

CAUTION: Shorted rear door driver circuits can cause additional Actuator Circuit Test messages to set for circuits where no condition exists to cause a fault.

CAUTION: To ensure a proper diagnosis, repair all Short Too Complex messages first, all rear door driver circuit related messages second, all common door driver circuit related messages third, and all front door driver circuit related messages last.

CAUTION: The DRBIII® can display up to three Actuator Circuit Test messages at a time. After repairing each Actuator Circuit Test message, cycle the ignition switch, then rerun the Actuator Circuit Test to ensure no new messages exist.

The Short Too Complex message:
- indicates that a specific determination of which lines are shorted could not be made.
- is caused by more than three drivers being shorted in the same direction. For example, four drivers all shorted to ground, or two or more drivers shorted with at least one driver shorted to ignition/battery and one driver shorted to ground.
Messages displaying:
- XXX Driver/Circuit Shorted to Ignition/Battery will set on a per-driver basis.
- XXX Driver/Circuit Shorted to Ground will set on a per-driver basis.
- the same two drivers/circuits shorted to ignition/battery as-well-as shorted to ground indicates that two actuator driver circuits are shorted together.
When the test returns passed, then troubleshooting should proceed to clearing faults and running the HVAC Door Recalibration system test as a final check of system health.