Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc u1712 lost lin communication with battery "1" monitor module

Subaru Legacy BN/BS (2015-2019) Service Manual / Engine (diagnostics)(h4do) / Diagnostic procedure with diagnostic trouble code (dtc) / Dtc u1712 lost lin communication with battery "1" monitor module

DTC DETECTING CONDITION:

Immediately at fault recognition

CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode Clear Memory Mode > OPERATION, and Inspection Mode Inspection Mode > PROCEDURE.

WIRING DIAGRAM:

• Engine Electrical System ENGINE TYPE FB (WITHOUT PUSH BUTTON START) Engine Electrical System > WIRING DIAGRAM

• Engine Electrical System ENGINE TYPE FB (WITH PUSH BUTTON START) Engine Electrical System > WIRING DIAGRAM

STEP	CHECK	YES	NO
1.CHECK DTC. Check for DTC. Read Diagnostic Trouble Code (DTC)	Is U1712 displayed in «Present fault»-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U1712 LOST LIN COMMUNICATION WITH BATTERY "1" MONITOR MODULE	The circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.
2.CHECK ECM CONNECTOR. Check the connecting condition of ECM connector.	Is the ECM connector correctly connected-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U1712 LOST LIN COMMUNICATION WITH BATTERY "1" MONITOR MODULE	Connect the ECM connector correctly.
3.CHECK HARNESS BETWEEN BATTERY AND BATTERY SENSOR CONNECTOR. 1) Turn the ignition switch to OFF. 2) Disconnect the ground terminal from battery sensor. NOTE 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 --	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U1712 LOST LIN COMMUNICATION WITH BATTERY "1" MONITOR MODULE	Repair the open circuit in harness between battery positive cable terminal and battery sensor connector.
4.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 --	Repair the poor contact of ECM connector or battery sensor connector.	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

1. OUTLINE OF DIAGNOSIS

Detect malfunction of LIN communication.

Judge as NG when LIN communication failure has occurred with the battery sensor.

2. COMPONENT DESCRIPTION

(Common Specifications)

Communication protocol: LIN 2.0

Communication Speed: 19.20 kbps

3. EXECUTION CONDITION

Secondary Parameters	Execution condition
Battery voltage	≥ 10.9 V

4. GENERAL DRIVING CYCLE

Always perform the diagnosis continuously.

5. DIAGNOSTIC METHOD

If the duration of time while the following conditions are met is longer than the time indicated, judge as NG.

Judgment Value

Malfunction Criteria

Threshold Value

Data received from control modules connected to LIN

No change

Checksum error

Time Needed for Diagnosis: 2 seconds

Malfunction Indicator Light Illumination: Does not illuminate.

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