CAN Communication Circuit Check: Procedure: Diag-Can

NOTE: When measuring the resistance of CAN communication circuit, measure it in sleep status.
To enter sleep status

With ignition switch OFF and key or switch operation stopped, keep the doors, trunk, and rear gate all closed for one minute or more.
On models with keyless access function, keep the access key 2 m or more away from the vehicle.

Wiring diagram:

CAN communication system Refer to WIRING SYSTEM>CAN COMMUNICATION SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

CHECK BASIC DIAGNOSTIC PROCEDURE.
Check that the basic diagnosis has been performed up to step 7.

NOTE: Possible defective parts can be narrowed easily by inspection using Subaru Select Monitor before performing "CHECK CAN COMMUNICATION CIRCUIT" using a tester.

Was the basic diagnostic procedure performed?

Yes: Go to 2.

No: Perform the basic diagnostic procedure. Refer to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .
CHECK SHORT CIRCUIT TO GROUND OF HARNESS BETWEEN DATA LINK CONNECTOR AND BODY INTEGRATED UNIT.
1. Turn the ignition switch to OFF.
2. Disconnect the body integrated unit connector.
3. Using a tester, measure the resistance between data link connector and chassis ground.
  Connector & terminal
  
  (B40) No. 6 - Chassis ground:
  
  (B40) No. 14 - Chassis ground:
Is the resistance less than 10 Ω?

Yes: Repair or replace the short circuit to ground in harness between the data link connector and the body integrated unit.

No: Go to 3.
CHECK SHORT CIRCUIT TO BATTERY IN HARNESS BETWEEN DATA LINK CONNECTOR AND BODY INTEGRATED UNIT.
1. Turn the ignition switch to ON.
2. Using the tester, measure the voltage between data link connector and chassis ground.
  Connector & terminal
  
  (B40) No. 6 (+) - Chassis ground (-):
  
  (B40) No. 14 (+) - Chassis ground (-):
Is the voltage less than 5 V?

Yes: Go to 4.

No: Repair or replace the short circuit to battery in harness between the data link connector and the body integrated unit.
CHECK FOR SHORT CIRCUIT BETWEEN LINES IN HARNESS BETWEEN DATA LINK CONNECTOR AND BODY INTEGRATED UNIT.
1. Turn the ignition switch to OFF.
2. Using the tester, measure the resistance between terminals of data link connector.
  Connector & terminal
  
  (B40) No. 6 - No. 14:
Is the resistance 1 MΩ or more?

Yes: Go to 5.

No: Repair or replace the short circuit between lines of the harness between data link connector and body integrated unit.
CHECK END RESISTANCE.
1. Connect the body integrated unit connector.
2. Using the tester, measure the resistance between terminals of data link connector.
  Connector & terminal
  
  (B40) No. 6 - No. 14:
Is the resistance 114 - 126 Ω?

Yes: CAN communication circuit is normal.

No: Replace the body integrated unit. Refer to SECURITY AND LOCKS>BODY INTEGRATED UNIT .