System Diagnostics

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

• DTCs are displayed by the DRBIII(R).
• 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(R).
• checks A/C system performance based on evaporator temperature sensor input.
• will fail if evaporator temperature is below 18.3°C (65°F) when initiating the test.
• will pass if the evaporator temperature drops 6.7°C (20°F).
• faults display on the DRBIII(R) as test messages only after running the test.
• faults will not display on the DRBIII(R) as Diagnostic Trouble Codes.
• will cause the A/C mode switch status indicator to flash while the test is running.
  1. If the test fails, the status indicator will continue to flash until either the test returns passed or the ignition key is cycled. It will also prevent the EBL mode switch status indicator from indicating EBL operating status. However, the EBL mode switch will continue to function in this state.

The HVAC Door Recalibration function:

• is actuated with the DRBIII(R).
  1. After completing HVAC Door Recalibration, the DRBIII(R) will display the current total span of each door actuator. It is important to note this information before proceeding with diagnosing door calibration fault messages.
• homes and repositions door actuators.
• monitors for door span faults.
• faults display on the DRBIII(R) as test messages only after running the test.
• faults will not display on the DRBIII(R) as Diagnostic Trouble Codes.
• will cause the EBL mode switch status indicator to flash while the test is running.
  1. If the test fails, the status indicator will continue to flash until either the test returns passed or the ignition key is cycled. It will also prevent the A/C mode switch status indicator from indicating A/C status. However, the A/C mode switch will continue to function in this state.

The Actuator Circuit Test:

• is actuated with the DRBIII(R).
• 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(R) as test messages only after running the test.
• faults will not display on the DRBIII(R) as Diagnostic Trouble Codes.