AIR CONDITIONING SYSTEM, Diagnostic DTC:B144A

DTC Code DTC Name
B144A Air Outlet DEF Damper Control Servo Motor Circuit

DESCRIPTION

The No. 3 air conditioning radiator damper servo sub-assembly (MODE DEF) 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. 3 air conditioning radiator damper servo sub-assembly (MODE DEF) to the appropriate position. This adjusts the amount of air passing through the heater core after passing the evaporator and controls the temperature of the output air. 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
B144A Air Outlet DEF Damper Control Servo Motor Circuit

  • Diagnosis condition: No. 3 air conditioning radiator damper servo sub-assembly (MODE DEF) 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. 3 air conditioning radiator damper servo sub-assembly (MODE DEF)

  • Air conditioning harness assembly

  • Air conditioning amplifier assembly

 Memorized
DTC Detection Condition combination Table
Vehicle Condition
Pattern 1 Pattern 2
Diagnosis Condition No. 3 air conditioning radiator damper servo sub-assembly (MODE DEF) operating ○ ○
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

B004UMQE54

CAUTION / NOTICE / HINT

Note


  • 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

Tech Tips

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

PROCEDURE


  1. CHECK FOR DTC


    1. Check for DTCs.

      Click here


      Body Electrical > Air Conditioner > Trouble Codes
      Result
      Result Proceed to
      DTC B144A is output A
      DTC B144A and B1497 are output. B

    B

    GO TO DTC B1497 Click here

    A

  2. CHECK NO. 3 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY


    1. Check for No. 3 air conditioning radiator damper servo sub-assembly is installed correctly.

      OK
      No. 3 air conditioning radiator damper servo sub-assembly is installed correctly.
      Result
      Proceed to
      OK
      NG

    NG

    REINSTALL NO. 3 AIR CONDITIONING RADIATOR DAMPER SERVO SUB-ASSEMBLY Click here

    OK

  3. CHECK NO. 3 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. 3 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 TECHSTREAM (AIR MIX SERVO TARG PULSE(D))


    1. Remove the No. 3 air conditioning radiator damper servo sub-assembly and No. 1 air conditioning radiator damper servo sub-assembly.

      Click here

    2. Connect the No. 2 air conditioning radiator damper servo sub-assembly (driver side upper air mix) connector to No. 3 air conditioning radiator damper servo sub-assembly (MODE DEF).

    3. Connect the Techstream to the DLC3.

    4. Turn the power switch on (IG).

    5. Turn the Techstream 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
      Air Mix Servo Targ Pulse(D)

        for LHD:

      • No. 2 air conditioning radiator damper servo sub-assembly (driver side upper air mix) operation*


        for RHD:

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

      Min.: 128

      Max.: 383

        for LHD:

      • Operates between 254 to 326 pulses


        for RHD:

      • Operates between 186 to 258 pulses

      • *: Actually operates the No. 3 air conditioning radiator damper servo sub-assembly (MODE DEF).


      Body Electrical > Air Conditioner > Active Test
      Tester Display
      Air Mix Servo Targ Pulse(D)
      OK
      No. 3 air conditioning radiator damper servo sub-assembly (MODE DEF) is operated.
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE AIR CONDITIONING HARNESS ASSEMBLY Click here

    NG

  6. CHECK NO. 3 AIR CONDITIONING RADIATOR DAMPER SERVI SUB-ASSEMBLY


    1. Interchange the MODE DEF servo motor with driver side upper 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 B1446 is output A
      DTC B144A is output B
      DTCs are not output C

      Tech Tips

      Codes other than DTC B1446 and B144A may be output at this time, but they are not related to this check.


    A

    REPLACE NO. 3 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