DTC U0074: Control Module Communication Bus "Body-Can" Off

DTC detecting condition:

Detected when malfunction occurs in CAN line. (Bus off).

Trouble symptom:

In each screen, there are some items that are not displayed.

Favorite screen is not properly displayed.
Fuel economy screen is not properly displayed.
Ambient air temperature is displayed in bar display.
Only the energy flow screen (hybrid model), preventive safety screen, electrical parts operation status screen, Favorite screen, fuel economy screen, and setting transition screen are displayed.

Wiring diagram:

Except for hybrid model

Multi-function display (MFD) system Ref. to WIRING SYSTEM (IMPREZA MODEL)>MULTIFUNCTION DISPLAY (MFD) SYSTEM>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>MULTI-FUNCTION DISPLAY (MFD) SYSTEM>WIRING DIAGRAM .
CAN communication system Ref. to WIRING SYSTEM (IMPREZA MODEL)>CAN COMMUNICATION SYSTEM>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>CAN COMMUNICATION SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

Hybrid model

Multi-function display (MFD) system Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>MULTI-FUNCTION DISPLAY (MFD) SYSTEM>WIRING DIAGRAM .

CAN communication system Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>CAN COMMUNICATION SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to MULTI-FUNCTION DISPLAY (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION .

CHECK DTC .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor, perform the clear memory of [Multi-Function Display]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
3. Turn the ignition switch to OFF.
4. Disconnect the MFD connector and reconnect it.
5. Turn the ignition switch to ON.
6. Read the DTC of [Multi-Function Display] using the Subaru Select Monitor. Ref. to MULTI-FUNCTION DISPLAY (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC U0074 displayed? (Current malfunction)

Yes: Go to 2.

No: Even if DTC (past malfunction) is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
CHECK HARNESS (GROUND SHORT CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Disconnect the MFD connector.
3. Using a tester, measure the resistance between MFD connector and chassis ground.
  Connector and terminal
  
  (i122) No. 19 - Chassis ground:
  
  (i122) No. 20 - Chassis ground:
Is the resistance 10 kΩ or more?

Yes: Go to 3.

No: Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
CHECK HARNESS (OPEN CIRCUIT) .
1. Disconnect the body integrated unit connector (except for hybrid model) or central gateway control module connector (for hybrid model).
2. Use a tester and measure the resistance between the MFD connector and body integrated unit connector (except for hybrid model) or central gateway control module connector (for hybrid model).
  Connector and terminal
  
  Except for hybrid model
  
  (i122) No. 19 - (B281) No. 17:
  
  (i122) No. 20 - (B281) No. 19:
  
  Hybrid model
  
  (i122) No. 19 - (i366) No. 15:
  
  (i122) No. 20 - (i366) No. 16:
Is the resistance 10 Ω or less?

Yes: Go to 4.

No: Repair or replace the open circuit of harness.
CHECK LAN SYSTEM .
Perform the diagnosis for LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE . Ref. to LAN SYSTEM (DIAGNOSTICS) (HEV)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

Is the check result OK?

Yes: Replace the MFD. Ref. to INSTRUMENTATION/DRIVER INFO>MULTI-FUNCTION DISPLAY (MFD) .

No: Perform the inspection according to the diagnosis for LAN system.