DTC U0073: Control Module Communication Bus Off

DTC detecting condition: 

Central gateway control module communication is shut down because of high speed CAN error.

Trouble symptom: 

CAN communication is not normal.

1. CHECK CAN COMMUNICATION HARNESS  .

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

2. CHECK DTC  .
   1. Start the engine.
   2. Using the Subaru Select Monitor, read all DTCs. Ref. to LAN System (Diagnostics)>Diagnostic Trouble Code (DTC) .

      Is DTC U0073 displayed? (Current malfunction)

      Yes  : Go to  3 .

      No  : It may be a temporary poor contact. Using the Subaru Select Monitor, perform the clear memory of all DTCs. Ref. to COMMON (DIAG)>CLEAR MEMORY .

3. CHECK CAN COMMUNICATION CIRCUIT  .

   Check CAN communication circuit. Ref. to LAN SYSTEM (DIAGNOSTICS)>CAN COMMUNICATION CIRCUIT CHECK>PROCEDURE .

   Is CAN communication circuit faulty?

   Yes  : Repair the faulty portion, following the diagnosis procedure.

   No  : Go to  4 .

4. CHECK DTC  .
   1. Perform the inspection using the DTC check sheet. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST>CHECK USING THE DTC CHECK SHEET .
   2. Using the Subaru Select Monitor, read all DTCs. Ref. to LAN System (Diagnostics)>Diagnostic Trouble Code (DTC) .

      Is DTC U0073 displayed? (Current malfunction)

      Yes  : Go to  5 .

      No  : System is normal.

5. CHECK CONTROL MODULE  .
   1. Turn the ignition switch to OFF.
   2. Disconnect control modules other than the central gateway control module in order.
      NOTE: When disconnecting the control module of end resistance, connect resistance of 120 Ω between CAN Hi and CAN Lo as an alternative of end resistance.
   3. Turn the ignition switch to ON.
   4. Using the Subaru Select Monitor, read all DTCs. Ref. to LAN System (Diagnostics)>Diagnostic Trouble Code (DTC) .

      Is there any control module that DTC U0073 is not detected as current malfunction?

      Yes  : Replace the control module.

      No  : Repeat step  5 until DTC U0073 is not detected.