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Home >> Lexus >> 2024 >> TX 350 Base, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 17 (Hybrid Control System - Diagnostic Codes (6 Of 6) & Circuit Tests) >> HYBRID CONTROL SYSTEM (for PHEV Model) >> DTC U1157-87: Lost Communication with Drive Motor Control Module "A" (ch3) Missing Message [12/2023 - ] >> Procedure

DTC U1157-87: Lost Communication with Drive Motor Control Module "A" (ch3) Missing Message [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 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 from the negative (-) auxiliary battery terminal.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      B88-2 (CA5H) - B88-1 (CA5L) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω Ω
      B88-2 (CA5H) or B88-1 (CA5L) - Other supply terminals Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      B88-2 (CA5H) or B88-1 (CA5L) - Body ground Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the cable from the negative (-) auxiliary battery terminal.

    Result: 

    NG 

    See step  7

    Result: 

    OK 

    See step  2

  2. CHECK HYBRID MOTOR CONTROL INVERTER ASSEMBLY (+B, +B VOLTAGE) 
    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.
    • Reconnect the cable from the negative (-) auxiliary battery terminal.
    • 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
      B89-36 (+B) - Body ground Ignition switch ON 11 to 14 V V
      B89-35 (+B2) - Body ground Ignition switch off 11 to 14 V V
      GTY1236762Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Hybrid Motor Control Inverter Assembly)
      NOTE:

      Turning the ignition switch to ON with the hybrid motor control inverter assembly connector disconnected causes other DTCs to be stored. Clear the DTCs after performing this inspection.

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Turn the ignition switch off.
    • Disconnect the cable from the negative (-) auxiliary battery terminal.
    • Reconnect the hybrid motor control inverter assembly connector.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (HYBRID MOTOR CONTROL INVERTER ASSEMBLY - BODY GROUND) 
    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.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      B89-9 (GND1) - Body ground Ignition switch off Below 1 Ω Ω
      B89-8 (GND2) - Body ground Ignition switch off Below 1 Ω Ω
      GTY1236766Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Hybrid Motor Control Inverter Assembly)

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the hybrid motor control inverter assembly connector.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. REPLACE HYBRID MOTOR CONTROL INVERTER ASSEMBLY (MOTOR GENERATOR CONTROL ECU (MG ECU)) 

    HINT: 

    Refer to REMOVAL [12/2023 - ]

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    See step  5

  5. CLEAR DTC 

    Refer to PROCEDURE - Step 2

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    See step  6

  6. CHECK WHETHER DTC OUTPUT RECURS (HYBRID CONTROL) 
    1. Read the DTCs.

      Powertrain > Hybrid Control > Trouble Codes 

      Result

      Result Proceed to
      DTC U1157-87 is output A
      DTC U1157-87 is not output B

    Result: 

    A 

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

    Result: 

    B 

    END 

  7. INSPECT HYBRID VEHICLE CONTROL ECU ASSEMBLY 

    Pre-procedure1

    • Disconnect the cable from the negative (-) auxiliary battery terminal.
    • Disconnect the hybrid vehicle control ECU assembly connector.

      HINT: 

      Check the other ECUs are connected.

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

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      B88-2 (CA5H) - B88-1 (CA5L) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Ω
      B88-2 (CA5H) or B88-1 (CA5L) - Other supply terminals Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      B88-2 (CA5H) or B88-1 (CA5L) - Body ground Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

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

    Result: 

    OK 

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

    Result: 

    NG 

    See step  8

  8. INSPECT HYBRID MOTOR CONTROL INVERTER ASSEMBLY (MOTOR GENERATOR CONTROL ECU (MG ECU)) 
    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 from the negative (-) auxiliary battery terminal.
    • Disconnect the hybrid motor control inverter assembly connector.

      HINT: 

      Check the other ECUs are connected.

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

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      B89-3 (HMH1) - B89-4 (HML1) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Ω
      B89-3 (HMH1) or B89-4 (HML1) - Other supply terminals Cable disconnected from negative (-) auxiliary battery terminal 6 kΩ or higher kΩ
      B89-3 (HMH1) or B89-4 (HML1) - Body ground Cable disconnected from 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 from the negative (-) auxiliary battery terminal.

    Result: 

    OK 

    REPLACE HYBRID MOTOR CONTROL INVERTER ASSEMBLY (MOTOR GENERATOR CONTROL ECU (MG ECU)). Refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    See step  9

  9. CHECK WIRE HARNESS AND CONNECTOR (HYBRID MOTOR CONTROL INVERTER ASSEMBLY - 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 hybrid motor control inverter assembly connector.
    • Disconnect the EV 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
      B89-3 (HMH1) - J72-32 (HMH3) Ignition switch off Below 1 Ω Ω
      B89-4 (HML1) - J72-33 (HML3) Ignition switch off Below 1 Ω Ω
      B89-3 (HMH1) - J72-32 (HMH3) - Body ground and other terminals Ignition switch off 10 kΩ or higher kΩ
      B89-4 (HML1) or J72-33 (HML3) - Body ground Ignition switch off 10 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

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

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  10

  10. CHECK EV MOTOR CONTROL INVERTER ASSEMBLY (EV MOTOR CONTROL INVERTER ASSEMBLY - HYBRID VEHICLE CONTROL ECU 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 EV motor control inverter assembly connector.
    • Disconnect the hybrid vehicle control ECU assembly connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      J72-34 (HMH4) - B88-2 (CA5H) Ignition switch off Below 1 Ω Ω
      J72-35 (HML4) - B88-1 (CA5L) Ignition switch off Below 1 Ω Ω
      J72-34 (HMH4) or B88-2 (CA5H) - Body ground and other terminals Ignition switch off 10 kΩ or higher kΩ
      J72-35 (HML4) or B88-1 (CA5L) - Body ground Ignition switch off 10 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the hybrid vehicle control ECU assembly connector.
    • Reconnect the EV motor control inverter assembly connector.

    Result: 

    OK 

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

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (HV LOCAL BUS) 

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