DTC U1712: Lost Lin Communication With Battery "1" Monitor Module: Notes

DTC detecting condition:

Immediately at fault recognition

CAUTION: Use the check board when measuring the ECM terminal voltage and resistance. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE CHECK BOARD .

NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

CHECK DTC.
Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (DIAG)>DIAGNOSTIC TROUBLE CODE (DTC) .

Is DTC U1712 displayed? (Current malfunction)

Yes : Go to 2.

No : The circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.
CHECK ECM CONNECTOR.
Check the connecting condition of ECM connector.

Is the ECM connector correctly connected?

Yes : Go to 3.

No : Connect the ECM connector correctly.
CHECK HARNESS BETWEEN BATTERY AND BATTERY SENSOR CONNECTOR (OPEN).
1. Turn the ignition switch to OFF.
2. Disconnect the ground terminal from battery sensor. Ref. to REPAIR CONTENTS>NOTE>BATTERY .
3. Disconnect the connector from battery sensor.
4. Disconnect the positive terminal of battery.
5. Measure the resistance of the harness between battery positive cable terminal and battery sensor connector.
  Connector & terminal.
  
  Positive cable terminal - (B9) No. 1:
  
  Positive cable terminal - (B9) No. 2:
Is the resistance less than 1 Ω?

Yes : Go to 4.

No : Repair the open circuit in harness between battery positive cable terminal and battery sensor connector.
CHECK HARNESS BETWEEN ECM CONNECTOR AND BATTERY SENSOR CONNECTOR (OPEN).
1. Disconnect the connector from ECM.
2. Measure the resistance of harness between ECM connector and battery sensor connector.
  Connector & terminal.
  
  (B9) No. 3 - (B134) No. 56:
Is the resistance less than 1 Ω?

Yes : Repair the poor contact of ECM connector or battery sensor connector.

No : Repair the open circuit in harness between ECM connector and battery sensor connector.