AIR CONDITIONING SYSTEM, Diagnostic DTC:B1446

DTC Code DTC Name
B1446 Air Mix Damper Control Servo Motor Circuit (Driver Side)

DESCRIPTION

The No. 1 air conditioning radiator damper servo sub-assembly (driver side upper air mix) (for LHD) or No. 4 air conditioning radiator damper servo sub-assembly (driver side upper air mix)(for RHD) sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on these signals to move the No. 1 air conditioning radiator damper servo sub-assembly (driver side upper air mix) (for LHD) or No. 4 air conditioning radiator damper servo sub-assembly (driver side upper air mix) (for RHD) to the appropriate position. As a result, the amount of air passing through the heater core after passing through the evaporator is adjusted, and the temperature of the air blowing toward the driver side is controlled.

The air conditioning amplifier assembly communicates with the servo through a communication/driver IC and wiring assembly called the air conditioning harness assembly.

DTC No. Detection Item DTC Detection Condition Trouble Area Memory
B1446 Air Mix Damper Control Servo Motor Circuit (Driver Side)

  • Diagnosis condition: No. 1 air conditioning radiator damper servo sub-assembly (driver side upper air mix) (for LHD) or No. 4 air conditioning radiator damper servo sub-assembly (driver side upper air mix) (for RHD) operation

  • Malfunction status: The damper servo operation request signal is output but the position information of the servo does not change or servo is malfunctioning

  • Detection time: Continuously for 30 seconds or more

  • No. 1 air conditioning radiator damper servo sub-assembly (driver side upper air mix) (for LHD)

  • No. 4 air conditioning radiator damper servo sub-assembly (driver side upper air mix) (for RHD)

  • Air conditioning harness assembly

  • Air conditioning amplifier assembly

 Memorized
DTC Detection Condition Combination Table
Vehicle Condition
Pattern 1 Pattern 2
Diagnosis Condition No. 1 air conditioning radiator damper servo sub-assembly (driver side upper air mix) (for LHD) or No. 4 air conditioning radiator damper servo sub-assembly (driver side upper air mix) (for RHD) operation ○ ○
Malfunction Status The damper servo operation request signal is output but the position information of the servo does not change ○ -
The damper servo operation request signal is output but the position information of the servo is malfunctioning - ○
Detection Time Continuously for 30 seconds or more Continuously for 30 seconds or more
Trip Count 1 trip 1 trip

Tech Tips

If the conditions match either of these patterns, a DTC will be output.

WIRING DIAGRAM

Figure 1. for LHD:

B000UUOE12

Figure 2. for RHD:

B000UUOE18

CAUTION / NOTICE / HINT

Note


  • When DTC B1446 and B1453 are output at same time, there would be malfunctioning on No. 1 air conditioning radiator damper servo sub-assembly (for LHD) or No. 4 air conditioning radiator damper servo sub-assembly (driver side upper air mix)(for RHD).

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

  • When installing the damper servo motor, make sure to install it correctly.

  • When the servo motor is replaced, be sure to perform servo motor initialization.

    Click here

PROCEDURE


  1. CHECK FOR DTC


    1. Check for DTCs.

      Click here


      Body Electrical > Air Conditioner > Trouble Codes
      Result
      Result Proceed to
      DTC B1446 is output (for LHD) A
      DTC B1446 is output (for RHD) B
      DTC B1446 and B1497 are output C

    B

    CHECK NO. 4 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY Click here

    C

    GO TO DTC B1497 Click here

    A

  2. CHECK NO. 1 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY


    1. Check for No. 1 air conditioning radiator damper servo sub-assembly is installed correctly.

      OK
      No. 1 air conditioning radiator damper servo sub-assembly is installed correctly.
      Result
      Proceed to
      OK
      NG

    NG

    REINSTALL NO. 1 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY Click here

    OK

  3. CHECK NO. 1 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY (MOTOR, LINK, DAMPER)


    1. Check for a wire harness caught between the links of the motors and dampers.

      OK
      No wire harnesses are caught between the links of the motors and dampers.
      Result
      Proceed to
      OK
      NG

    NG

    REMOVE PINCHED WIRE HARNESS

    OK

  4. CHECK AIR CONDITIONING RADIATOR ASSEMBLY (DAMPER)


    1. Remove the No. 1 air conditioning radiator damper servo sub-assembly.

      Click here

    2. Operate the dampers by hand.

      OK
      The dampers are easily operated by hand.
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE AIR CONDITIONING RADIATOR ASSEMBLY

    OK

  5. PERFORM ACTIVE TEST USING GTS (COOL A/M SERVO PULSE(P))


    1. Remove the No. 1 air conditioning radiator damper servo sub-assembly.

      Click here

    2. Connect the No. 1 air conditioning radiator damper servo sub-assembly (driver side lower side air mix) connector to No. 1 air conditioning radiator damper servo sub-assembly (driver side upper side air mix).

    3. Connect the GTS to the DLC3.

    4. Turn the engine switch on (IG).

    5. Turn the GTS on.

    6. Enter the following menus: Body Electrical / Air Conditioner / Active Test.

    7. Check the operation by referring to the table below.


      Body Electrical > Air Conditioner > Active Test
      Tester Display Measurement Item Control Range Restrict Condition
      Cool A/M Servo Pulse(D) No. 1 air conditioning radiator damper servo sub-assembly (driver side lower air mix) operation*

      Min.: 128

      Max.: 383

      		 Operates between 154 and 258 pulses

      • *: Actually operates the No. 1 air conditioning radiator damper servo sub-assembly (driver side upper air mix).


      Body Electrical > Air Conditioner > Active Test
      Tester Display
      Cool A/M Servo Pulse(D)
      OK
      No. 1 air conditioning radiator damper servo sub-assembly (driver side upper air mix) is operated.
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE AIR CONDITIONING HARNESS ASSEMBLY Click here

    NG

  6. CHECK NO. 1 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY


    1. Interchange the driver side upper air mix servo motor with driver side lower air mix servo motor and connect the connectors to them.

      Click here

    2. Clear the DTCs.

      Click here

    3. Check for DTCs.

      Click here

      Result
      Result Proceed to
      DTC B1453 is output A
      DTC B1446 is output B
      DTCs are not output C

      Tech Tips

      Codes other than DTC B1446 and B1453 may be output at this time, but they are not related to this check.


    A

    REPLACE NO. 1 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY Click here

    B

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    C

    USE SIMULATION METHOD TO CHECK Click here

  7. CHECK NO. 4 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY


    1. Check for No. 4 air conditioning radiator damper servo sub-assembly is installed correctly.

      OK
      No. 4 air conditioning radiator damper servo sub-assembly is installed correctly.
      Result
      Proceed to
      OK
      NG

    NG

    REINSTALL NO. 4 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY Click here

    OK

  8. CHECK NO. 4 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY (MOTOR, LINK, DAMPER)


    1. Check for a wire harness caught between the links of the motors and dampers.

      OK
      No wire harnesses are caught between the links of the motors and dampers.
      Result
      Proceed to
      OK
      NG

    NG

    REMOVE PINCHED WIRE HARNESS

    OK

  9. CHECK AIR CONDITIONING RADIATOR ASSEMBLY (DAMPER)


    1. Remove the No. 4 air conditioning radiator damper servo sub-assembly.

      Click here

    2. Operate the dampers by hand.

      OK
      The dampers are easily operated by hand.
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE AIR CONDITIONING RADIATOR ASSEMBLY

    OK

  10. PERFORM ACTIVE TEST USING GTS (COOL A/M SERVO PULSE(P))


    1. Remove the No. 4 air conditioning radiator damper servo sub-assembly.

      Click here

    2. Connect the No. 4 air conditioning radiator damper servo sub-assembly (driver side lower side air mix) connector to No. 4 air conditioning radiator damper servo sub-assembly (driver side upper side air mix).

    3. Connect the GTS to the DLC3.

    4. Turn the engine switch on (IG).

    5. Turn the GTS on.

    6. Enter the following menus: Body Electrical / Air Conditioner / Active Test.

    7. Check the operation by referring to the table below.


      Body Electrical > Air Conditioner > Active Test
      Tester Display Measurement Item Control Range Restrict Condition
      Cool A/M Servo Pulse(D) No. 4 air conditioning radiator damper servo sub-assembly (driver side lower air mix) operation*

      Min.: 128

      Max.: 383

      		 Operates between 154 and 258 pulses

      • *: Actually operates the No. 4 air conditioning radiator damper servo sub-assembly (driver side upper air mix).


      Body Electrical > Air Conditioner > Active Test
      Tester Display
      Cool A/M Servo Pulse(D)
      OK
      No. 4 air conditioning radiator damper servo sub-assembly (driver side upper air mix) is operated.
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE AIR CONDITIONING HARNESS ASSEMBLY Click here

    NG

  11. CHECK NO. 4 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY


    1. Interchange the driver side upper air mix servo motor with driver side lower air mix servo motor and connect the connectors to them.

      Click here

    2. Clear the DTCs.

      Click here

    3. Check for DTCs.

      Click here

      Result
      Result Proceed to
      DTC B1453 is output A
      DTC B1446 is output B
      DTCs are not output C

      Tech Tips

      Codes other than DTC B1446 and B1453 may be output at this time, but they are not related to this check.


    A

    REPLACE NO. 4 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY Click here

    B

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    C

    USE SIMULATION METHOD TO CHECK Click here