DTC U0424: Invalid Data Received From HVAC Control Module

DTC detecting condition:

Defective data was transmitted from A/C control panel.

Trouble symptom:

Cooperation control of air conditioner does not operate properly.

CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>GENERAL DESCRIPTION>CAUTION .

CHECK CAN COMMUNICATION HARNESS .
Perform the basic diagnostic procedure to check for fault in CAN communication harness. Ref. to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>BASIC DIAGNOSTIC PROCEDURE .

Was the basic diagnostic procedure performed up to step 7?

Yes: Go to 2.

No: Perform the basic diagnostic procedure. Ref. to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>BASIC DIAGNOSTIC PROCEDURE .
CHECK DTC (OTHER THAN U-CODE) .
Check the displayed DTC.

Is DTC other than U*** displayed? (Current malfunction)

Yes: Perform the diagnosis for DTCs other than the displayed U-code.

No: Go to 3.
CHECK DTC (U-CODE) .
Check the displayed DTC.

Is DTC for the bus off or the data no-receive displayed? (Current malfunction)

Yes: Perform the diagnosis for DTCs for the displayed bus off or the data no-receive.

No: Go to 4.
CHECK DTC .
Check the displayed DTC.

Is DTC U0424 displayed? (Current malfunction)

Yes: Go to 5.

No: Go to 7.
CHECK DTC .
1. Turn the ignition switch to OFF.
2. Disconnect the A/C control panel connector.
3. Connect the disconnected connectors.
4. Turn the ignition switch to ON.
5. Using the Subaru Select Monitor, read all DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC U0424 displayed? (Current malfunction)

Yes: Go to 6.

No: Go to 7.
CHECK DTC .
Using the Subaru Select Monitor, read all DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>DIAGNOSTIC TROUBLE CODE (DTC) .

Is DTC U0424 detected in several modules? (Current malfunction)

Yes: Replace the A/C control panel. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)>CONTROL PANEL .

No: Replace the module that the DTC has been detected.
CHECK HARNESS .
1. Shake the harness, and check for poor contact.
2. Using the Subaru Select Monitor, read all DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC U0424 displayed? (Current malfunction)

Yes: Repair the poor contact of harness, or replace the harness.

No: Go to 8.
CHECK CONNECTOR .
Check the connector used for high speed CAN for poor contact.

Is there poor contact of connector?

Yes: Repair the connector that has poor contact, or replace harness.

No: It is possible that temporary poor communication occurs. Delete the DTC.