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Home >> Lexus >> 2024 >> TX 350 Base, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 113 (Motor Generator Control System - Diagnostic Codes (2 Of 2)) >> MOTOR GENERATOR CONTROL SYSTEM (for 1Motor-HEV Model) >> DTC U11B9-87: Lost Communication with ECM/PCM "A" (ch6) Missing Message [09/2023 - ] >> Procedure

DTC U11B9-87: Lost Communication with ECM/PCM "A" (ch6) Missing Message [09/2023 - ]: Procedure

WARNING: This page is about a different car, the 2024 Lexus TX 500h. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK CAN BUS MAIN WIRE (ML-BUS) 
    WARNING:

    Be sure to wear insulated gloves.

    Pre-procedure1

    • Check that the service plug grip is not installed.
      NOTE:

      After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the service information because this may cause a malfunction.

    • Disconnect the cable to the negative (-) auxiliary battery terminal.
    • Disconnect the hybrid motor control inverter assembly connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      C46-12 (HMH1) - C46-13 (HML1) Disconnect the cable to the negative (-) auxiliary battery terminal 108 to 132 Ω Ω
      C46-15 (HMH2) - C46-14 (HML2) Disconnect the cable to the negative (-) auxiliary battery terminal 108 to 132 Ω Ω
      C46-12 (HMH1) or C46-13 (HML1) - Other power source terminals Disconnect the cable to the negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      C46-15 (HMH2) or C46-14 (HML2) - Other power source terminals Disconnect the cable to the negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      C46-12 (HMH1) or C46-13 (HML1) - Other terminals and body ground Disconnect the cable to the negative (-) auxiliary battery terminal 200 kΩ or higher kΩ
      C46-15 (HMH2) or C46-14 (HML2) - Other terminals and body ground Disconnect the cable to the negative (-) auxiliary battery terminal 200 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the hybrid motor control inverter assembly connector.
    • Reconnect the cable to the negative (-) auxiliary battery terminal.

    Result: 

    NG 

    See step  9

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (HYBRID MOTOR CONTROL INVERTER ASSEMBLY - ECM) 
    WARNING:

    Be sure to wear insulated gloves.

    Pre-procedure1

    • Check that the service plug grip is not installed.
      NOTE:

      After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the service information because this may cause a malfunction.

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

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      C46-12 (HMH1) - B77-18 (CFDP) Ignition switch off Below 1 Ω Ω
      C46-13 (HML1) - B77-17 (CFDN) Ignition switch off Below 1 Ω Ω
      C46-12 (HMH1) or B77-18 (CFDP) - Other terminals and body ground Ignition switch off 10 kΩ or higher kΩ
      C46-13 (HML1) or B77-17 (CFDN) - Other terminals and body ground Ignition switch off 10 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the ECM connector.
    • Reconnect the hybrid motor control inverter assembly connector.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  3

  3. CHECK ECM (+B, +B2, +B3 VOLTAGE) 

    Pre-procedure1

    • Disconnect the ECM connector.
    • Turn the ignition switch to ON.
    • Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      C27-12 (+B) - Body ground Ignition switch ON 11 to 14 V V
      C27-11 (+B2) - Body ground Ignition switch ON 11 to 14 V V
      C27-10 (+B3) - Body ground Ignition switch ON 11 to 14 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Turn the ignition switch off.
    • Reconnect the ECM connector.

    Result: 

    NG 

    REPAIR OR REPLACE ECU POWER SOURCE CIRCUIT. Refer to  ECU Power Source Circuit [09/2023 - ] 

    Result: 

    OK 

    See step  4

  4. CHECK ECM (IGR VOLTAGE) 

    Pre-procedure1

    • Disconnect the ECM connector.
    • Turn the ignition switch to ON.
    • Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      B77-22 (IGR) - Body ground Ignition switch ON 11 to 14 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Turn the ignition switch off.
    • Reconnect the ECM connector.

    Result: 

    NG 

    REPAIR OR REPLACE ECM POWER SOURCE CIRCUIT. Refer to  ECM Power Source Circuit [09/2023 - ] 

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND) 

    Pre-procedure1

    • Disconnect the ECM connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      B77-9 (E1) - Body ground Ignition switch off Below 1 Ω Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the ECM connector.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  6

  6. REPLACE ECM 

    HINT: 

    Refer to REMOVAL [09/2023 - ]

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    See step  7

  7. CLEAR DTC 
    1. Clear the DTCs.

      Powertrain > Motor Generator > Clear DTCs 

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  8

  8. DTC OUTPUT (MOTOR GENERATOR) 

    Pre-procedure1

    • Turn the ignition switch to ON and wait for 2 minutes or more.
    • Check for DTCs.

      Powertrain > Motor Generator > Trouble Codes 

      Result

      Result Proceed to
      U11B9-87 is output A
      U11B9-87 is not output B

    Post-procedure1

    • Turn the ignition switch off.

    Result: 

    A 

    REPLACE HYBRID MOTOR CONTROL INVERTER ASSEMBLY. Refer to  REMOVAL [09/2023 - ] 

    Result: 

    B 

    END 

  9. INSPECT ECM 

    Pre-procedure1

    • Disconnect the cable to the negative (-) auxiliary battery terminal.
    • Disconnect the ECM connector.

      HINT: 

      Check the other ECUs connected.

    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      B77-18 (CFDP) - B77-17 (CFDN) Disconnect the cable to the negative (-) auxiliary battery terminal 108 to 132 Ω Ω
      B77-18 (CFDP) or B77-17 (CFDN) - Other power source terminals Disconnect the cable to the negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      B77-18 (CFDP) or B77-17 (CFDN) - Other terminals and body ground Disconnect the cable to the negative (-) auxiliary battery terminal 200 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the ECM connector.
    • Reconnect the cable to the negative (-) auxiliary battery terminal.

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [09/2023 - ] 

    Result: 

    NG 

    See step  10

  10. INSPECT HYBRID VEHICLE CONTROL ECU ASSEMBLY 

    Pre-procedure1

    • Disconnect the cable to the negative (-) auxiliary battery terminal.
    • Disconnect the hybrid vehicle control ECU connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      B21-2 (CA5H) - B21-1 (CA5L) Disconnect the cable to the negative (-) auxiliary battery terminal 54 to 69 Ω Ω
      B21-2 (CA5H) or B21-1 (CA5L) - Other power source terminals Disconnect the cable to the negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      B21-2 (CA5H) or B21-1 (CA5L) - Other terminals and body ground Disconnect the cable to the negative (-) auxiliary battery terminal 200 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the hybrid vehicle control ECU connector.
    • Reconnect the cable to the negative (-) auxiliary battery terminal.

    Result: 

    OK 

    REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY. Refer to  REMOVAL [09/2023 - 12/2023]  , or refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    See step  11

  11. INSPECT TCM 

    Pre-procedure1

    • Disconnect the cable to the negative (-) auxiliary battery terminal.
    • Disconnect the TCM connector.

      HINT: 

      Check the other ECUs connected.

    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      C25-15 (CANU) - C25-16 (CAND) Disconnect the cable to the negative (-) auxiliary battery terminal 108 to 132 Ω Ω
      C25-15 (CANU) or C25-16 (CAND) - Other power source terminals Disconnect the cable to the negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      C25-15 (CANU) or C25-16 (CAND) - Other terminals and body ground Disconnect the cable to the negative (-) auxiliary battery terminal 200 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the TCM connector.
    • Reconnect the cable to the negative (-) auxiliary battery terminal.

    Result: 

    OK 

    REPLACE TCM. Refer to  REMOVAL [09/2023 - ] 

    Result: 

    NG 

    See step  12

  12. INSPECT EV MOTOR CONTROL INVERTER ASSEMBLY 
    WARNING:

    Be sure to wear insulated gloves.

    Pre-procedure1

    • Check that the service plug grip is not installed.
      NOTE:

      After removing the service plug grip, do not turn the ignition switch to ON (READY), unless instructed by the service information because this may cause a malfunction.

    • Disconnect the cable to the negative (-) auxiliary battery terminal.
    • Disconnect the EV motor control inverter assembly connector.

      HINT: 

      Check the other ECUs connected.

    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      J72-32 (HMH3) - J72-33 (HML3) Disconnect the cable to the negative (-) auxiliary battery terminal 108 to 132 Ω Ω
      J72-34 (HMH4) - J72-35 (HML4) Disconnect the cable to the negative (-) auxiliary battery terminal 108 to 132 Ω Ω
      J72-32 (HMH3) or J72-33 (HML3) - Other power source terminals Disconnect the cable to the negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      J72-34 (HMH4) or J72-35 (HML4) - Other power source terminals Disconnect the cable to the negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      J72-32 (HMH3) or J72-33 (HML3) - Other terminals and body ground Disconnect the cable to the negative (-) auxiliary battery terminal 200 kΩ or higher kΩ
      J72-34 (HMH4) or J72-35 (HML4) - Other terminals and body ground Disconnect the cable to the negative (-) auxiliary battery terminal 200 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the EV motor control inverter assembly connector.
    • Reconnect the cable to the negative (-) auxiliary battery terminal.

    Result: 

    OK 

    REPLACE EV MOTOR CONTROL INVERTER ASSEMBLY. Refer to  REMOVAL [09/2023 - 12/2023]  , or refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ML-BUS) 

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