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

WARNING: This page is about a different variant/trim than selected.

DTC detecting condition:

Immediately at fault recognition

CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Clear Memory Mode . and Inspection Mode Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Inspection Mode .
Use the check board when measuring the ECM terminal voltage and resistance.

Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM>Engine Electrical System>WIRING DIAGRAM .

Fig 1: Engine Electrical System Wiring Diagram (LIN Communication With Battery Lost)

Courtesy of SUBARU OF AMERICA, INC.

CHECK DTC.
Check for DTC. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>Read Diagnostic Trouble Code (DTC) .

Is U1712 displayed in [DTC]?
- Yes: Go to 2.
- No: The circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis.
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.
1. Turn the ignition switch to OFF.
2. Disconnect the ground terminal from battery sensor. Ref. to STARTING/CHARGING SYSTEMS(H4DO)>Battery>REMOVAL . Ref. to NOTE>BASIC REPAIR HINT>WHEN REMOVING 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 - (B78) No. 1:

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 CONNECTOR.
1. Disconnect the connector from ECM.
2. Measure the resistance of harness between battery positive terminal and battery sensor connector.
  Connector & terminal
  
  (B78) No. 1 - Battery positive terminal:
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