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Home >> Lexus >> 2019 >> ES 350 Luxury >> Repair and Diagnosis >> External Pages >> Different car >> Section 78 (Engine Control System (A25A-FKS) - Diagnostic Codes (11 Of 12)) >> SFI System >> DTC P26CA-31: Engine Coolant Pump No Signal [08/2020 - 08/2021] >> Procedure

DTC P26CA-31: Engine Coolant Pump No Signal [08/2020 - 08/2021]: Procedure

WARNING: This page is about a different car, the 2024 Lexus ES 250, 2023 Lexus ES 250, 2022 Lexus ES 250, and 2021 Lexus ES 250. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK TERMINAL VOLTAGE (POWER SOURCE OF ENGINE WATER PUMP ASSEMBLY (WATER INLET HOUSING)) 
    GTY948540Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Engine Water Pump Assembly (Water Inlet Housing))
    1. Disconnect the engine water pump assembly (water inlet housing) connector.
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      C66-5 (NWP) - Body ground Engine switch on (IG) 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  8

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (ENGINE WATER PUMP ASSEMBLY (WATER INLET HOUSING) - BODY GROUND) 
    1. Disconnect the engine water pump assembly (water inlet housing) connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      C66-3 (PGN2) - Body ground Always Below 1 Ω
      C66-6 (PGND) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  3

  3. CHECK TERMINAL VOLTAGE (POWER SOURCE OF ENGINE WATER PUMP ASSEMBLY (WATER INLET HOUSING)) 
    GTY948385Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Engine Water Pump Assembly (Water Inlet Housing))
    1. Disconnect the engine water pump assembly (water inlet housing) connector.
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      C66-1 (+B2) - Body ground Engine switch on (IG) 11 to 14 V
      C66-4 (+B) - Body ground Engine switch on (IG) 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ENGINE WATER PUMP ASSEMBLY (WATER INLET HOUSING). Refer to  REMOVAL [08/2020 - 08/2021] 

    Result: 

    NG 

    See step  4

  4. INSPECT A/F HTR RELAY 
    1. Inspect the A/F HTR relay.

      Refer to PROCEDURE - Step 3

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE A/F HTR RELAY 

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (POWER SOURCE OF A/F HTR RELAY) 
    GTY774656Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *1 No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
    *2 A/F HTR Relay
    1. Remove the A/F HTR relay from the No. 1 engine room relay block and No. 1 junction block assembly.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      3 (A/F HTR relay) - Body ground Always 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - A/F HTR RELAY) 

    Result: 

    OK 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (A/F HTR RELAY - BODY GROUND) 
    1. Remove the A/F HTR relay from the No. 1 engine room relay block and No. 1 junction block assembly.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      1 (A/F HTR relay) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (A/F HTR RELAY - ENGINE WATER PUMP ASSEMBLY (WATER INLET HOUSING)) 
    1. Remove the A/F HTR relay from the No. 1 engine room relay block and No. 1 junction block assembly.
    2. Disconnect the engine water pump assembly (water inlet housing) connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      5 (A/F HTR relay) - C66-1 (+B2) Always Below 1 Ω
      5 (A/F HTR relay) - C66-4 (+B) Always Below 1 Ω
      5 (EFI-MAIN NO. 2 relay), C66-1 (+B2) or C66-4 (+B) - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (EFI-MAIN NO. 1 RELAY - A/F HTR RELAY) 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  8. CHECK HARNESS AND CONNECTOR (ENGINE WATER PUMP ASSEMBLY (WATER INLET HOUSING) - ECM) 
    1. Disconnect the engine water pump assembly (water inlet housing) connector.
    2. Disconnect the ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      C66-5 (NWP) - C77-51 (WPI) Always Below 1 Ω
      C66-5 (NWP) or C77-51 (WPI) - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [08/2020 - 08/2021] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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