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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 91 (Heating / Air Conditioning System (HV) - Diagnostic Codes (2 Of 3)) >> AIR CONDITIONING SYSTEM (for HV Model) >> DTC B1497: Communication Malfunction (Bus Ic) [12/2019 - 10/2022] >> Procedure

DTC B1497: Communication Malfunction (Bus Ic) [12/2019 - 10/2022]: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. PERFORM ACTIVE TEST USING GTS (SERVO PULSE) 
    1. Perform the Active Test according to the display on the GTS.

      Body Electrical > Air Conditioner > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      Air Mix Servo Targ Pulse(D) No. 1 air conditioning radiator damper servo sub-assembly (driver side air mix) pulse Min.: 128
      Max.: 383      		 Operates between 165 to 257 pulses
      Air Mix Servo Targ Pulse(P) No. 1 air conditioning radiator damper servo sub-assembly (front passenger side air mix) pulse Min.: 128
      Max.: 383      		 Operates between 255 to 347 pulses
      Air Outlet Servo Pulse (D) No. 2 air conditioning radiator damper servo sub-assembly (driver side mode) pulse Min.: 128
      Max.: 383      		 Operates between 164 to 278 pulses
      Air Inlet Damper Targ Pulse No. 1 blower damper servo sub-assembly pulse Min.: 128
      Max.: 383      		 Operates between 220 to 256 pulses
      Air Outlet Servo Pulse (P) No. 1 air conditioning radiator damper servo sub-assembly (front passenger side mode) pulse Min.: 128
      Max.: 383      		 Operates between 234 to 348 pulses

      Body Electrical > Air Conditioner > Active Test 

      Tester Display
      Air Mix Servo Targ Pulse(D)

      Body Electrical > Air Conditioner > Active Test 

      Tester Display
      Air Mix Servo Targ Pulse(P)

      Body Electrical > Air Conditioner > Active Test 

      Tester Display
      Air Outlet Servo Pulse (D)

      Body Electrical > Air Conditioner > Active Test 

      Tester Display
      Air Inlet Damper Targ Pulse

      Body Electrical > Air Conditioner > Active Test 

      Tester Display
      Air Outlet Servo Pulse (P)

      OK

      Damper servo motor is operated.

      Result

      Result  Proceed to
      All damper servo motors are not operated A
      Any damper servo motor is not operated B
      All damper servo motors are operated C

    Result: 

    B 

    REPLACE AIR CONDITIONING HARNESS ASSEMBLY. Refer to  DISASSEMBLY [12/2019 - 10/2022] 

    Result: 

    C 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022] 

    Result: 

    A 

    See step  2

  2. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY 
    1. Disconnect the z18 air conditioning amplifier assembly connector.
      GTY918000Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (Air Conditioning Amplifier Assembly)      		 - -
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      z18-2 (BUS G) - Body ground Always Below 1 Ω
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      z18-4 (B BUS) - z18-2 (BUS G) Ignition switch off 11 to 14 V
    4. Using an oscilloscope, check the waveform.
      Item Content
      Tester Connection z18-3 (BUS) - z18-2 (BUS G)
      Tool Setting 2 V/DIV., 20 μs/DIV.
      Condition Ignition switch ON

      OK

      The waveform displays properly.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE AIR CONDITIONING HARNESS ASSEMBLY. Refer to  DISASSEMBLY [12/2019 - 10/2022] 

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022] 

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