DTC B2605: Battery Control Low

DTC detecting condition: 

During the motor operation, voltage for power seat control module drops for a moment. (7.5 V or less)

Trouble symptom: 

• Seat positions cannot be memorized.
• Seat operation is possible with manual operation, but not with memory function.

Wiring diagram: 

Power seat system Ref. to WIRING SYSTEM>POWER SEAT SYSTEM>WIRING DIAGRAM>DRIVER'S SEAT (WITH MEMORY) .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC. 
   1. Turn the ignition switch to ON.
   2. Read the DTC of the power seat control module using the Subaru Select Monitor. Ref. to POWER SEAT MEMORY SYSTEM (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC) .

   Is DTC B2605 displayed? (Current malfunction)

   Yes  Go to  2 .

   No  Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and 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 DTC. 
   1. Perform the clear memory operation. Ref. to POWER SEAT MEMORY SYSTEM (DIAGNOSTICS)>Clear Memory Mode>OPERATION .
   2. Turn the ignition switch to OFF.
   3. Disconnect, and then connect the power seat control module connector.
   4. Turn the ignition switch to ON.
   5. Move the power seat.
   6. Read the DTC of the power seat control module using the Subaru Select Monitor. Ref. to POWER SEAT MEMORY SYSTEM (DIAGNOSTICS)>Read Diagnostic Trouble Code (DTC) .

   Is DTC B2605 displayed? (Current malfunction)

   Yes  Go to  3 .

   No  Repair or replace the poor contact of connector.

3. CHECK POWER SEAT CONTROL MODULE. 

   Using Subaru Select Monitor, check the display of power seat control module current data «Battery Terminal Voltage». Ref. to POWER SEAT MEMORY SYSTEM (DIAGNOSTICS)>Read Current Data>OPERATION .

   Is the voltage 8.5 - 16.5 V?

   Yes  Go to  5 .

   No  Go to  4 .

4. CHECK HARNESS (OPEN CIRCUIT). 
   1. Turn the ignition switch to OFF.
   2. Disconnect the power seat control module connector.
   3. Turn the ignition switch to ON.
   4. Using the tester, measure the voltage between power seat control module connector and chassis ground.

   Connector & terminal 

   (R155) No. 10 (+) - Chassis ground (-):

   (R155) No. 11 (+) - Chassis ground (-):

   (R156) No. 3 (+) - Chassis ground (-):

   (R156) No. 8 (+) - Chassis ground (-):

   Is the voltage 8.5 - 16.5 V?

   Yes  Replace the power seat control module. Ref. to SEATS>POWER SEAT System>REMOVAL>POWER SEAT CONTROL MODULE (SEAT WITH MEMORY FUNCTION) .

   No  Repair the open circuit in harness between power seat control module connector and fuse.

5. CHECK BATTERY VOLTAGE. 

   Measure the battery voltage while the power seat is in operation.

   Is the voltage 8.5 - 16.5 V?

   Yes  Ask the user if the power window or passenger's power seat was operated or cranking was performed while the driver's power seat is in operation.

   NOTE: Even when the battery voltage is normal under ordinary circumstance, the voltage may drop to 7.5 V or less in some cases, for example at cranking.

   No  Check the battery. Ref. to STARTING/CHARGING SYSTEMS (H4DO)>BATTERY . Ref. to STARTING/CHARGING SYSTEMS (H6DO)>BATTERY .