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DTC U0291-00: Lost Communication with Gear Shift Control Module "B" (System 2) 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 DTC OUTPUT (HEALTH CHECK) 

    Pre-procedure1

    • Turn the ignition switch to ON.
    • Using the GTS, perform a Health Check.

      Result

      Result Proceed to
      U0291-00 only is output A
      U0291-00 and other DTCs are output B

    Post-procedure1

    • Turn the ignition switch off.

    Result: 

    B 

    GO TO DTC CHART. Refer To  DIAGNOSTIC TROUBLE CODE CHART [09/2023 - ] 

    Result: 

    A 

    See step  2

  2. CHECK FOR SHORT TO GROUND IN CAN BUS LINE (ECU CONNECTED) 

    Pre-procedure1

    • Disconnect the cable from the negative (-) auxiliary battery terminal.
    • Measure the resistance according to the value(s) in the table below.
      GTY1230521Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Shift Control ECU (Transmission Floor Shift Assembly))

      Standard Resistance (Check for Short)

      Tester Connection Condition Specified Condition Result
      D25-21 (CA3H) or D25-6 (CA3L) - Body ground Cable from negative (-) auxiliary battery terminal disconnected 200 Ω or higher Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Connect the cable to the negative (-) auxiliary battery terminal.

    Result: 

    NG 

    See step  5

    Result: 

    OK 

    See step  3

  3. CHECK FOR OPEN AND SHORT TO OTHER TERMINALS IN CAN BUS LINE (SHIFT CONTROL ECU - SHIFT ACTUATOR ECU) 

    Pre-procedure1

    • Disconnect the cable from the negative (-) auxiliary battery terminal.
    • Disconnect the C53 shift actuator ECU (shift control actuator 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
      C53-4 (CA3H) - C53-3 (CA3L) Cable from negative (-) auxiliary battery terminal disconnected 54 to 69 Ω Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Connect the shift actuator ECU (shift control actuator assembly) connector.
    • Connect the cable to the negative (-) auxiliary battery terminal.

    Result: 

    OK 

    REPLACE SHIFT ACTUATOR ECU (SHIFT CONTROL ACTUATOR ASSEMBLY). Refer to  REMOVAL [09/2023 - ] 

    Result: 

    NG 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (SHIFT CONTROL ECU - SHIFT ACTUATOR ECU) 

    Pre-procedure1

    • Disconnect the D25 shift control ECU (transmission floor shift assembly) connector.
    • Disconnect the C53 shift actuator ECU (shift control actuator assembly) connector.
    • Disconnect the D44 hybrid vehicle control ECU connector.
    • Disconnect the z11 battery voltage sensor connector.
    • Disconnect the C47 EV converter assembly connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      D25-21 (CA3H) - C53-4 (CA3H) Always Below 1 Ω Ω
      D25-6 (CA3L) - C53-3 (CA3L) Always Below 1 Ω Ω
      C53-4 (CA3H) - C53-3 (CA3L) Always 1 MΩ or higher MΩ
      D25-21 (CA3H) - D25-6 (CA3L) Always 1 MΩ or higher MΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Connect the EV converter assembly connector.
    • Connect the battery voltage sensor connector.
    • Connect the hybrid vehicle control ECU connector.
    • Connect the shift actuator ECU (shift control actuator assembly) connector.
    • Connect the shift control ECU (transmission floor shift assembly) connector.

    Result: 

    OK 

    GO TO CAN COMMUNICATION SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [09/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR IN CAN BUS LINE (SHIFT CONTROL ECU - SHIFT ACTUATOR ECU) 

  5. CHECK FOR SHORT TO GROUND IN CAN BUS LINE (SHIFT ACTUATOR ECU DISCONNECTED) 

    Pre-procedure1

    • Disconnect the cable from the negative (-) auxiliary battery terminal.
    • Disconnect the C53 shift actuator ECU (shift control actuator assembly) connectors.
    • Measure the resistance according to the value(s) in the table below.
      GTY1230522Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Shift Control ECU (Transmission Floor Shift Assembly))

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      D25-21 (CA3H) or D25-6 (CA3L) - Body ground Cable from negative (-) auxiliary battery terminal disconnected 200 Ω or higher Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the shift actuator ECU (shift control actuator assembly) connector.
    • Connect the cable to the negative (-) auxiliary battery terminal.

    Result: 

    OK 

    REPLACE SHIFT ACTUATOR ECU (SHIFT CONTROL ACTUATOR ASSEMBLY). Refer to  REMOVAL [09/2023 - ] 

    Result: 

    NG 

    See step  6

  6. CHECK FOR SHORT TO GROUND IN CAN BUS LINE (SHIFT CONTROL ECU DISCONNECTED) 

    Pre-procedure1

    • Disconnect the cable from the negative (-) auxiliary battery terminal.
    • Disconnect the D25 shift control ECU (transmission floor shift assembly) connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      D25-21 (CA3H) or D25-6 (CA3L) - Body ground Cable from negative (-) auxiliary battery terminal disconnected 200 Ω or higher Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the shift control ECU (transmission floor shift assembly) connector.
    • Connect the cable to the negative (-) auxiliary battery terminal.

    Result: 

    OK 

    REPLACE SHIFT CONTROL ECU (TRANSMISSION FLOOR SHIFT ASSEMBLY). Refer to  REMOVAL [09/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR IN CAN BUS LINE (SHIFT CONTROL ECU - SHIFT ACTUATOR ECU) 

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