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Home >> Lexus >> 2025 >> NX 350h >> Repair and Diagnosis >> External Pages >> Different car >> Section 71 (Heating / Air Conditioning System - Diagnostic Codes, Circuit Tests & Symptom Tests) >> AIR CONDITIONING SYSTEM (for Gasoline Model) >> Heater Water Pump Circuit [11/2021 - ] >> Procedure

Heater Water Pump Circuit [11/2021 - ]: Procedure

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  1. CHECK FOR DTC 
    1. Check for DTCs.

      Body Electrical > Power Integration No. 1 > Trouble Codes 

      Result

      Result Proceed to
      DTC B2352-04 is not output A
      DTC B2352-04 is output B

    Result: 

    B 

    REPLACE SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [11/2021 - ] 

    Result: 

    A 

    See step  2

  2. CHECK FOR VEHICLE CONTROL HISTORY (RoB) 
    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
      Water Pump Heater water pump assembly OFF / ON Operate with ignition switch on (engine running) and the vehicle stopped.

      Body Electrical > Air Conditioner > Active Test 

      Tester Display
      Water Pump
    2. Check for Vehicle Control History (RoB).

      Body Electrical > Power Integration No. 1 > Utility 

      Tester Display
      Vehicle Control History (RoB)

      Result

      Result Proceed to
      RoB X0A39 is not output A
      RoB X0A39 is output B

    Result: 

    B 

    See step  6

    Result: 

    A 

    See step  3

  3. INSPECT SEMICONDUCTOR POWER INTEGRATION ECU (OUTPUT SIGNAL) 
    1. Disconnect the A64 heater water pump assembly connector.
    2. 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
      Water Pump Heater water pump assembly OFF / ON Operate with ignition switch on (engine running) and the vehicle stopped.

      Body Electrical > Air Conditioner > Active Test 

      Tester Display
      Water Pump
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A64-2 (+B) - A64-1 (-) Active Test: ON 8 V or higher
      GTY1071795Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Heater Water Pump Assembly)

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE HEATER WATER PUMP ASSEMBLY. Refer to  REMOVAL [11/2021 - 03/2024]  , or refer to  REMOVAL [03/2024 - ] 

    Result: 

    NG 

    See step  4

  4. READ VALUE USING GTS 
    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
      Water Pump Heater water pump assembly OFF / ON Operate with ignition switch on (engine running) and the vehicle stopped.

      Body Electrical > Air Conditioner > Active Test 

      Tester Display
      Water Pump
    2. Read the Data List according to the display on the GTS.

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display Measurement Item Range Normal Condition Inspection Item
      A/C Water Pump Input Signal A/C water pump input OFF / ON OFF: A/C Water Pump is not input
      ON: A/C Water Pump is input      		 -

      Body Electrical > Power Integration No. 1 > Data List 

      Tester Display
      A/C Water Pump Input Signal

      OK

      When the Active Test is ON, the Data List is ON.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [11/2021 - ] 

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (SEMICONDUCTOR POWER INTEGRATION ECU - HEATER WATER PUMP ASSEMBLY) 
    1. Disconnect the A77 semiconductor power integration ECU connector.
    2. Disconnect the A64 heater water pump assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A77-3 (L) - A64-2 (+B) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [11/2021 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  6. INSPECT SEMICONDUCTOR POWER INTEGRATION ECU (OUTPUT SIGNAL) 
    1. Disconnect the A64 heater water pump assembly connector.
    2. 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
      Water Pump Heater water pump assembly OFF / ON Operate with ignition switch on (engine running) and the vehicle stopped.

      Body Electrical > Air Conditioner > Active Test 

      Tester Display
      Water Pump
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A64-2 (+B) - A64-1 (-) Active Test: ON 8 V or higher
      GTY1071795Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Heater Water Pump Assembly)

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE HEATER WATER PUMP ASSEMBLY. Refer to  REMOVAL [11/2021 - 03/2024]  , or refer to  REMOVAL [03/2024 - ] 

    Result: 

    NG 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (SEMICONDUCTOR POWER INTEGRATION ECU - HEATER WATER PUMP ASSEMBLY) 
    1. Disconnect the A77 semiconductor power integration ECU connector.
    2. Disconnect the A64 heater water pump assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A77-3 (L) or A64-2 (+B) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [11/2021 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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