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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Heating / Air Conditioning System (Except HV, W/ Auto A/C) - Circuit Tests & Symptom Tests >> AIR CONDITIONING SYSTEM (for Gasoline Model with Automatic Air Conditioning System) >> Heater Water Pump Circuit [12/2019 - ] >> Procedure

Heater Water Pump Circuit [12/2019 - ]: Procedure

  1. INSPECT A/C W/PMP RELAY (AIR CONDITIONING WATER PUMP RELAY) 

    Refer to ON-VEHICLE INSPECTION [12/2019 - 11/2023] , or refer to ON-VEHICLE INSPECTION [11/2023 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE A/C W/PMP RELAY (AIR CONDITIONING WATER PUMP RELAY) 

    Result: 

    OK 

    See step  2

  2. INSPECT HEATER WATER PUMP ASSEMBLY 

    Refer to INSPECTION [12/2019 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE HEATER WATER PUMP ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - ] 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (A/C W/PMP RELAY (AIR CONDITIONING WATER PUMP RELAY) - POWER SOURCE) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      1 (A/C W/PMP Relay (air conditioning water pump relay)) - Body ground Always 11 to 14 V
      3 (A/C W/PMP Relay (air conditioning water pump relay)) - Body ground Always 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (HEATER WATER PUMP ASSEMBLY - A/C W/PMP RELAY (AIR CONDITIONING WATER PUMP RELAY), BODY GROUND) 
    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A4-1 (-) - Body ground Always Below 1 Ω
      A4-2 (+B) - 5 (A/C W/PMP Relay (air conditioning water pump relay)) Always Below 1 Ω
      A4-2 (+B) or 5 (A/C W/PMP Relay (air conditioning water pump relay)) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (A/C W/PMP RELAY (AIR CONDITIONING WATER PUMP RELAY) - ENGINE STOP AND START ECU) 
    1. Disconnect the A34 engine stop and start ECU connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      2 (A/C W/PMP Relay (air conditioning water pump relay)) - A34-5 (WP) Always Below 1 Ω
      2 (A/C W/PMP Relay (air conditioning water pump relay)) or A34-5 (WP) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  6

  6. INSPECT ENGINE STOP AND START ECU 
    1. Reconnect the A34 engine stop and start ECU connector.
    2. Remove the engine stop and start ECU with the connectors still connected.

      Refer to REMOVAL [12/2019 - 10/2022] , or refer to REMOVAL [10/2022 - 11/2023] , or refer to REMOVAL [11/2023 - ]

    3. Measure the voltage according to the value(s) in the table below.
      GTY928746Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Engine Stop and Start ECU)      		 - -

      Standard Voltage

      Tester Connection Condition Specified Condition
      A34-5 (WP) - Body ground
      • Engine stopped by stop and start system
      • A/C switch: on
      		 0 V
      • Engine not stopped by stop and start system
      • A/C switch: on
      		 9.5 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023]  , or refer to  REMOVAL [11/2023 - ] 

    Result: 

    NG 

    REPLACE ENGINE STOP AND START ECU. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023]  , or refer to  REMOVAL [11/2023 - ] 

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