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) (H4DO)>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) (H4DO)>Basic Diagnostic Procedure>PROCEDURE .

Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM (CROSSTREK MODEL)>Engine Electrical System>WIRING DIAGRAM .

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 ENGINE (DIAGNOSTICS) (H4DO)>DIAGNOSTIC TROUBLE CODE (DTC) .

DTC Check

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 (OPEN) .
1. Turn the ignition switch to OFF.
2. Disconnect the ground terminal from battery sensor. Ref. to REPAIR CONTENTS>NOTE>SAFETY .
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 AND BATTERY SENSOR (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. 5:
Is the resistance less than 1 Ω?

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

No: Repair the harness and connector.
NOTE:
In this case, repair the following item:
- Open circuit in harness between ECM connector and battery sensor connector
- Poor contact of coupling connector