DTC P1531 Battery Current Sensor Circuit High: Notes

DTC DETECTING CONDITION: 

Immediately at fault recognition

WIRING DIAGRAM: 

• Engine Electrical System NON-TURBO MODEL (WITHOUT PUSH BUTTON START) Ref. to WIRING SYSTEM > Engine Electrical System >  NON-TURBO MODEL (WITHOUT PUSH BUTTON START)  .
• Engine Electrical System NON-TURBO MODEL (WITH PUSH BUTTON START) Ref. to WIRING SYSTEM > Engine Electrical System >  NON-TURBO MODEL (WITH PUSH BUTTON START)  .

1. CHECK CURRENT DATA  .
   1. Start the engine.
   2. Using the Subaru Select Monitor, read the value in [Battery current value].
      NOTE: For detailed operation procedures, refer to "Current Data Display For Engine". Ref. to ENGINE (DIAGNOSTICS) (H4DO) >  Subaru Select Monitor   .

   Is the value of [Battery current value] -100 A or less?

   Yes: Go to   2  .

   No: Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
2. CHECK HARNESS BETWEEN ECM AND BATTERY CURRENT SENSOR CONNECTOR  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from the battery current sensor.
   3. Start the engine.
   4. Using the Subaru Select Monitor, read the value in [Battery current value].
      NOTE: For detailed operation procedures, refer to "Current Data Display For Engine". Ref. to ENGINE (DIAGNOSTICS) (H4DO) >  Subaru Select Monitor   .

   Is the value of [Battery current value] -100 A or less?

   Yes: Repair the short circuit to power in the harness between ECM connector and battery current sensor connector.

   No: Go to   3  .

3. CHECK HARNESS BETWEEN ECM AND BATTERY CURRENT SENSOR CONNECTOR  .
   1. Turn the ignition switch to OFF.
   2. Measure the resistance of the harness between the battery current sensor connector and engine ground.

      Connector & terminal 

      (B472) No. 4 - Engine ground:

   Is the resistance less than 5 Ω?

   Yes: Go to   4  .

   No: Repair the harness and connector.

   NOTE: In this case, repair the following item:

   • Open circuit in harness between ECM connector and battery current sensor connector
   • Poor contact of joint connector
4. CHECK FOR POOR CONTACT  .

   Check for poor contact of the battery current sensor connector.

   Is there poor contact of the battery current sensor connector?

   Yes: Repair the poor contact of the battery current sensor connector.

   No: Replace the battery current sensor. Ref. to STARTING/CHARGING SYSTEMS (H4DO) >  BATTERY CURRENT & TEMPERATURE SENSOR  .