AIR CONDITIONING SYSTEM, Diagnostic DTC:B1491/91

DTC Code DTC Name
B1491/91 HV Battery Cool Down Servo Motor Circuit

DESCRIPTION

The HV battery cool down servo sends pulse signals to inform the air conditioning amplifier of the damper position. The air conditioning amplifier activates the motor (normal or reverse) based on these signals to move the HV battery cool down servo motor to the appropriate position, which controls the HV battery cool down modes.

Tech Tips

Confirm that no mechanical problem is present because this diagnostic code can be output when either a damper link or damper is mechanically locked.

DTC Code DTC Detection Condition Trouble Area
B1491/91 HV battery cool down servo motor damper position does not change even if air conditioning amplifier operates HV battery cool down servo motor

  • HV battery cool down servo motor

  • Rear air conditioning harness

  • Harness or connector between rear air conditioning harness and air conditioning amplifier

  • Air conditioning amplifier

WIRING DIAGRAM

A000U7JE15

PROCEDURE


  1. CHECK FOR DTC


    1. Clear the DTCs Click here.

    2. Check for DTCs Click here.

      Result
      Result Proceed to
      DTC B1491/91 is not output A
      DTC B1491/91 is output B
      DTC B1491/91 and B1497/97 are output C

    A

    USE SIMULATION METHOD TO CHECK Click here

    C

    GO TO DTC B1497/97 Click here

    B

  2. READ VALUE USING INTELLIGENT TESTER (BATTERY COOL DOWN SERVO MOTOR TARGET PULSE)


    1. Use the Data List to check if the servo motor is functioning properly.

      Air conditioner
      Tester Display Measurement Item / Range Normal Condition Diagnostic Note
      Batt Cool Down Servo Targ Pls

      HV battery cool down servo motor target pulse /

      Min.: 8, Max.: 30

      A/C intake air position: 8

      Interior intake air position: 30

      		 -
      OK
      HV battery cool down servo motor operates normally.

    2. Visually inspect the HV battery cool down servo motor.


      1. Visually inspect whether the HV battery cool down servo motor operates.

        OK
        The HV battery cool down servo motor operates.
        Result
        Result Proceed to
        The Data List value changes and the HV battery cool down servo motor operates (When troubleshooting according to the DTC output) A
        The Data List value changes and the HV battery cool down servo motor operates (When troubleshooting according to Problem Symptoms Table) B
        The Data List value does not change and the HV battery cool down servo motor does not operate C
        The Data List value changes, but the HV battery cool down servo motor does not operate D

    B

    PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    C

    REPLACE AIR CONDITIONING AMPLIFIER Click here

    D

    CHECK HARNESS AND CONNECTOR (REAR AIR CONDITIONING HARNESS - AIR CONDITIONING AMPLIFIER) Click here

    A

  3. CHECK FOR DTC


    1. Clear the DTCs Click here.

    2. Check for DTCs Click here.

      OK
      DTC B1491/91 is not output.

    OK

    USE SIMULATION METHOD TO CHECK Click here

    NG

    REPLACE AIR CONDITIONING AMPLIFIER Click here

  4. CHECK HARNESS AND CONNECTOR (REAR AIR CONDITIONING HARNESS - AIR CONDITIONING AMPLIFIER)

    A000UHLE01

    1. Disconnect the S90 rear air conditioning harness connector.

    2. Disconnect the L76 air conditioning amplifier connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      S90-12 (BRRG) - L76-12 (BRRG) Always Below 1 Ω
      S90-11 (BURR) - L76-13 (BURR)
      S90-10 (BRRB) - L76-14 (BRRB)
      L76-12 (BRRG) - Body ground Always 10 kΩ or higher
      L76-13 (BURR) - Body ground
      L76-14 (BRRB) - Body ground

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HV BATTERY COOL DOWN SERVO MOTOR


    1. Replace the HV battery cool down servo motor Click here.

      Tech Tips

      Since the servo motor cannot be inspected while it is removed from the vehicle, replace the servo motor with a normal one.

    2. Clear the DTCs Click here.

    3. Check for DTCs Click here.

      OK
      DTC B1491/91 is not output.

    OK

    END (HV BATTERY COOL DOWN SERVO MOTOR IS FAULTY)

    NG

  6. CHECK REAR AIR CONDITIONING HARNESS


    1. Replace the rear air conditioning harness Click here.

    2. Clear the DTCs Click here.

    3. Check for DTCs Click here.

      OK
      DTC B1491/91 is not output.

    OK

    END (REAR AIR CONDITIONING HARNESS IS FAULTY)

    NG

    REPLACE AIR CONDITIONING AMPLIFIER Click here