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Home >> Lexus >> 2024 >> RX 500h >> Repair and Diagnosis >> External Pages >> Different car >> Section 82 (Heating / Air Conditioning System - Diagnostic Codes (2 Of 3)) >> AIR CONDITIONING SYSTEM (for PHEV Model) >> DTC B14B0-87: Lost Communication with Heat Pump ECU (Local-CAN) Missing Message [08/2023 - ] >> Procedure

DTC B14B0-87: Lost Communication with Heat Pump ECU (Local-CAN) Missing Message [08/2023 - ]: Procedure

WARNING: This page is about a different car, the 2025 Lexus RX 450h+ and 2024 Lexus RX 450h+. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK DTC (AIR CONDITIONING SYSTEM) 
    1. Check if air conditioning system DTCs are output.

      Body Electrical > Air Conditioner > Trouble Codes 

      HINT: 

      Check even when the DTCs detected for temporary failures.

      Result

      Result Proceed to
      B1498-87 is not output A
      B1498-87 is output B
      Relevant DTC
      B1498-87 A/C Inverter Local Missing Message

    Result: 

    B 

    GO TO DIAGNOSTIC TROUBLE CODE CHART (B1498-87). Refer to  DTC B1498-87: A/C Inverter Local Missing Message [08/2023 - ] 

    Result: 

    A 

    See step  2

  2. CHECK CAN BUS WIRE (AIR CONDITIONING AMPLIFIER ASSEMBLY) 

    Pre-procedure1

    • Disconnect the cable from the negative (-) auxiliary battery terminal.
    • Disconnect the A61 heat pump ECU assembly connector.
    • Measure the resistance according to the value(s) in the table below.
      GTY1143602Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Heat Pump ECU Assembly)

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      A61-8 (CANP) - A61-9 (CANN) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Ω
      A61-8 (CANP) - Body ground Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Ω
      A61-9 (CANN) - Body ground Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Ω
      A61-8 (CANP) - Battery Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      A61-9 (CANN) - Battery Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    See step  5

    Result: 

    OK 

    See step  3

  3. CHECK CAN BUS WIRE (HEAT PUMP ECU ASSEMBLY) 

    Pre-procedure1

    • Disconnect the cable from the negative (-) auxiliary battery terminal.
    • Disconnect the C49 air conditioning amplifier assembly connector.
    • Measure the resistance according to the value(s) in the table below.
      GTY1206557Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Air Conditioning Amplifier Assembly)

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      C49-11 (CANP) - C49-12 (CANN) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Ω
      C49-11 (CANP) - Body ground Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Ω
      C49-12 (CANN) - Body ground Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Ω
      C49-11 (CANP) - Battery Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      C49-12 (CANN) - Battery Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    REPLACE HEAT PUMP ECU ASSEMBLY. Refer to  REMOVAL [08/2023 - ] 

    Result: 

    OK 

    See step  4

  4. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY 

    Pre-procedure1

    • Disconnect the A61 heat pump ECU assembly connector.
    • Check for pulses according to the value(s) in the table below.
      GTY1143602Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Heat Pump ECU Assembly)
      Tester Connection Condition Specified Condition
      A61-8 (CANP) - A61-9 (CANN) Ignition switch ON Pulse generation

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

    REPLACE HEAT PUMP ECU ASSEMBLY. Refer to  REMOVAL [08/2023 - ] 

    Result: 

    NG 

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

  5. CHECK CAN BUS WIRE (HEAT PUMP ECU ASSEMBLY) 

    Pre-procedure1

    • Disconnect the cable from the negative (-) auxiliary battery terminal.
    • Disconnect the C49 air conditioning amplifier assembly connector.
    • Measure the resistance according to the value(s) in the table below.
      GTY1206557Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Air Conditioning Amplifier Assembly)

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      C49-11 (CANP) - C49-12 (CANN) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Ω
      C49-11 (CANP) - Body ground Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Ω
      C49-12 (CANN) - Body ground Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Ω
      C49-11 (CANP) - Battery Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      C49-12 (CANN) - Battery Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

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

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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