Diagnostic Procedure for Subaru Select Monitor Communication: Inspection

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

Trouble symptom:

Communication with Front relay control module is impossible.

Detecting condition:

Defective harness connector
Power supply circuit malfunction
Front relay control module malfunctioning
Defective CAN communication circuit
Defective Subaru Select Monitor

Wiring diagram:

Headlight system Ref. to WIRING SYSTEM>HEADLIGHT SYSTEM>WIRING DIAGRAM
CAN communication system Ref. to WIRING SYSTEM>CAN COMMUNICATION SYSTEM>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to FRONT RELAY CONTROL MODULE (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION

CHECK POWER SUPPLY CIRCUIT .
Connect the interface for Subaru Select Monitor to the data link connector.

Does the interface for Subaru Select Monitor turn on?

Yes : Go to 4.

No : Go to 2.
CHECK POWER SUPPLY CIRCUIT .
1. Turn the ignition switch to ON.
2. Using the tester, measure the voltage between data link connector (i221) and chassis ground.
  Connector & terminal
  
  (i221) No. 8 (+) - Chassis ground (-):
  
  (i221) No. 16 (+) - Chassis ground (-):
Is the voltage 10 V or more?

Yes : Go to 3.

No : Repair the power supply circuit.
NOTE:
In this case, repair the following item:
- Open or ground short circuit of harness between battery and data link connector
- Blown out of fuse (M/B fuse No. 2, F/B fuse No. 3)
CHECK HARNESS BETWEEN DATA LINK CONNECTOR AND CHASSIS GROUND (OPEN) .
1. Turn the ignition switch to OFF.
2. Using the tester, measure the resistance between data link connector (i221) and chassis ground.
  Connector & terminal
  
  (i221) No. 4 - Chassis ground:
  
  (i221) No. 5 - Chassis ground:
Is the resistance less than 5 Ω?

Yes : Check for poor contact of the data link connector, and repair a fault, if any.

Or, if the interface for Subaru Select Monitor is turned ON, Go to 4.

No : Repair the harness and connector.

If the interface for Subaru Select Monitor is not turned ON, replace the interface and harness for Subaru Select Monitor.
CHECK INSTALLATION OF Front relay control module CONNECTOR .
Check the Front relay control module connector.

Is the Front relay control module connectors (B68, B69) inserted into the Front relay control module until they lock?

Yes : Perform the diagnosis for LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE

No : Insert the Front relay control module connector to Front relay control module.

Or, repair the connector if it is faulty.