Diagnostic Procedure for Subaru Select Monitor Communication: Inspection

Trouble symptom: 

Cannot communicate with [P-HEV Hybrid Powertrain Control].

Detecting condition: 

• Defective Wire harness connector
• Power supply circuit malfunction
• Defective Hybrid vehicle control ECU assembly
• Defective CAN communication circuit
• Defective Subaru Select Monitor

Wiring diagram: 

Hybrid system Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>HYBRID ELECTRIC VEHICLE SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK FUSE  .
   1. Turn the ignition switch to OFF.
   2. Check the fuse. Ref. to HYBRID ELECTRIC VEHICLE>RELAY AND FUSE .

   Is there any fault?

   Yes  : Replace the fuse. If the replaced fuse has blown out immediately, repair the short circuit to ground in Wire harness between fuse - Hybrid vehicle control ECU assembly.

   No  : Go to  2.

2. CHECK POWER SUPPLY CIRCUIT (OPEN)  .
   1. Disconnect the Hybrid vehicle control ECU assembly connector.
   2. Turn the ignition switch to ON.
   3. Using a tester, measure the voltage between Hybrid vehicle control ECU assembly connector and chassis ground.

      Connector & terminal 

      (B606) No. 2 (+) - Chassis ground (-):

      (i370) No. 1 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes  : Go to  3.

   No  : Repair or replace the Wire harness between fuse and Hybrid vehicle control ECU assembly connector.

3. CHECK GROUND CIRCUIT (OPEN)  .
   1. Turn the ignition switch to OFF.
   2. Using a tester, measure the resistance between Hybrid vehicle control ECU assembly connector and chassis ground.

      Connector & terminal 

      (B605) No. 2 - Chassis ground:

      (i369) No. 2 - Chassis ground:

      (i369) No. 6 - Chassis ground:

      (i370) No. 6 - Chassis ground:

   Is the resistance less than 1 Ω?

   Yes  : Go to  4.

   No  : Repair or replace the Wire harness between Hybrid vehicle control ECU assembly connector and chassis ground.

4. CHECK LAN SYSTEM  .
   1. Restore the vehicle to its original state.
   2. Inspect LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS) (HEV)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

   Is there any fault?

   Yes  : Perform the inspection according to the diagnosis for LAN system.

   No  : Go to  5.

5. CHECK Hybrid vehicle control ECU assembly  .

   Communicate with [P-HEV Hybrid Powertrain Control].

   Is communication possible?

   Yes  : 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 Wire harness may be the cause.

   No  : Replace Hybrid vehicle control ECU assembly. Ref. to HYBRID ELECTRIC VEHICLE>HYBRID POWERTRAIN CONTROL MODULE .