Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Procedure For Subaru Select Monitor Communication: Inspection
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:
CAN communication system Ref. to WIRING SYSTEM>CAN COMMUNICATION SYSTEM>WIRING DIAGRAM .
Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to BODY CONTROL/COMMUNICATION SYSTEM>GENERAL DESCRIPTION>CAUTION .
- CHECK POWER SUPPLY CIRCUIT
.
- Connect the interface for Subaru Select Monitor to the data link connector. COMMON (DIAGNOSTICS)>DATA LINK CONNECTOR
- Does the interface for Subaru Select Monitor turn on?
Connector & terminal
Yes: Go to 4 .
No: Go to 2
- CHECK POWER SUPPLY CIRCUIT
.
- Turn the ignition switch to ON. (Engine OFF)
- Using the tester, measure the voltage between data link connector 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 No. 2, F/B fuse No. 3)
- CHECK HARNESS CONNECTOR BETWEEN Front relay control module AND CHASSIS GROUND
.
- Turn the ignition switch to OFF.
- Using the tester, measure the resistance between data link connector 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. When no fault is found, Go to 4 .
No: Repair the harness and connector.
- CHECK INSTALLATION OF Front relay control module CONNECTOR
.
Turn the ignition switch to OFF.
Is the Front relay control module connectors (B68, B69) inserted into the Front relay control module until they lock?
Yes: Check the LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .
No: Insert the Front relay control module connector to Front relay control module. Repair the connector if the connector is faulty.
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.