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DTC P26F4-31: Coolant Pump "C" Control Circuit No Signal [12/2023 - ]: Procedure

WARNING: This page is about a different car, the 2024 Lexus TX 550h+. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK FUSE (OIL PMP RR) 

    Pre-procedure1

    • Remove the OIL PMP RR fuse from the No. 1 engine room relay block assembly.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      OIL PMP RR fuse Always Below 1 Ω Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Install the OIL PMP RR fuse.

    Result: 

    NG 

    REPLACE FUSE (OIL PMP RR) 

    Result: 

    OK 

    See step  2

  2. INSPECT RELAY (OIL PMP RR) 

    Pre-procedure1

    • Remove the OIL PMP RR relay from the No. 1 engine room relay block assembly.
    • Measure the resistance according to the value(s) in the table below.
      GTY1131774Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 OIL PMP RR Relay

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      3 - 5 Auxiliary battery voltage not applied between terminals 1 and 2 10 kΩ or higher
      3 - 5 Auxiliary battery voltage applied between terminals 1 and 2 Below 1 Ω Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Install the OIL PMP RR relay.

    Result: 

    NG 

    REPLACE OIL PMP RR RELAY 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (OIL PMP RR FUSE - OIL PMP RR RELAY) 

    Pre-procedure1

    • Remove the OIL PMP RR fuse from the No. 1 engine room relay block assembly.
    • Remove the OIL PMP RR relay from the No. 1 engine room relay block assembly.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition Result
      2 (OIL PMP RR fuse) - 3 (OIL PMP RR relay) Ignition switch off Below 1 Ω Ω

      Standard Resistance (Check for Short)

      Tester Connection Condition Specified Condition Result
      2 (OIL PMP RR fuse) or 3 (OIL PMP RR relay) - Body ground and other terminals Ignition switch off 10 kΩ or higher
      NOTE:

      Do not apply excessive force when using the probes of the tester to perform the inspection. If excessive force is used, the terminals will be damaged.

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Install the OIL PMP RR relay.
    • Install the OIL PMP RR fuse.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (OIL PMP RR RELAY - BODY GROUND) 

    Pre-procedure1

    • Remove the OIL PMP RR relay from the No. 1 engine room relay block assembly.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      2 (OIL PMP RR relay) - Body ground Ignition switch off Below 1 Ω Ω
      NOTE:

      Do not apply excessive force when using the probes of the tester to perform the inspection. If excessive force is used, the terminals will be damaged.

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Install the OIL PMP RR relay.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (EV MOTOR CONTROL INVERTER ASSEMBLY - OIL PUMP ASSEMBLY) 

    Pre-procedure1

    • Disconnect the EV motor control inverter assembly connector.
    • Disconnect the oil pump assembly connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition Result
      J75-7 (RNOP) - J73-2 (RNOP) Ignition switch off Below 1 Ω Ω
      J75-1 (ROPM) - J73-3 (ROPM) Ignition switch off Below 1 Ω Ω

      Standard Resistance (Check for Short)

      Tester Connection Condition Specified Condition Result
      J75-7 (RNOP) or J73-2 (RNOP) - Body ground and other terminals Ignition switch off 10 kΩ or higher
      J75-1 (ROPM) or J73-3 (ROPM) - Body ground and other terminals Ignition switch off 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the oil pump assembly connector.
    • Reconnect the EV motor control inverter assembly connector.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  6

  6. INSPECT EV MOTOR CONTROL INVERTER ASSEMBLY 

    Pre-procedure1

    • Disconnect the EV motor control inverter assembly connector.
    • Measure the resistance according to the value(s) in the table below.
      GTY1230070Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component without harness connected
      (EV Motor Control Inverter Assembly)

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      J75-7 (RNOP) - Body ground Ignition switch off 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the EV motor control inverter assembly connector.

    Result: 

    OK 

    REPLACE REAR TRANSAXLE WITH MOTOR AND INVERTER ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    REPLACE EV MOTOR CONTROL INVERTER ASSEMBLY. Refer to  REMOVAL [12/2023 - ]