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ECU Power Source Circuit [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 HARNESS AND CONNECTOR (BATT TERMINAL VOLTAGE) 
    1. Measure the voltage according to the value(s) in the table below.
      GTY1239643Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Shift Control ECU (Transmission Floor Shift Assembly))

      Standard Voltage

      Tester Connection Condition Specified Condition
      D25-2 (BATT) - Body ground Ignition switch off 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  7

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (IGCT, IGP TERMINAL VOLTAGE) 
    1. Turn the ignition switch to ON.
    2. Measure the voltage according to the value(s) in the table below.
      GTY1239642Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Shift Control ECU (Transmission Floor Shift Assembly))

      Standard Voltage

      Tester Connection Condition Specified Condition
      D25-3 (IGCT) - Body ground Ignition switch ON 11 to 14 V
      D25-1 (IGP) - Body ground Ignition switch ON 11 to 14 V
    3. Turn the Ignition switch off.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  8

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (SHIFT CONTROL ECU - BODY GROUND) 
    1. Disconnect the D25 shift control ECU (transmission floor shift assembly) connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      D25-9 (E1) - Body ground Always Below 1 Ω
      D25-23 (E12) - Body ground Always Below 1 Ω
    3. Reconnect the shift control ECU (transmission floor shift assembly) connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (SHIFT CONTROL ECU - BODY GROUND) 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (MA1, BAT1 TERMINAL VOLTAGE) 
    1. Disconnect the C53 and C64 shift actuator ECU (shift control actuator assembly) connectors.
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      C53-1 (MA1) - Body ground Ignition switch off 11 to 14 V
      C64-8 (BAT1) - Body ground Ignition switch off 11 to 14 V
    3. Reconnect the shift actuator ECU (shift control actuator assembly) connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  9

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (IGCT TERMINAL VOLTAGE) 
    1. Disconnect the C53 shift actuator ECU (shift control actuator assembly) connector.
    2. Turn the ignition switch to ON.
      NOTE:

      If the ignition switch is turned to ON with the connector disconnected, other DTCs will be stored. Be sure to clear the DTCs after the inspection.

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      C53-5 (IGC1) - Body ground Ignition switch ON 11 to 14 V
    4. Turn the Ignition switch off.
    5. Reconnect the shift actuator ECU (shift control actuator assembly) connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (SHIFT ACTUATOR ECU - NO. 1 ENGINE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY) 

    Result: 

    OK 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (SHIFT ACTUATOR ECU - BODY GROUND) 
    1. Disconnect the C53 shift actuator ECU (shift control actuator assembly) connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      C53-2 (E01) - Body ground Always Below 1 Ω
      C53-7 (E02) - Body ground Always Below 1 Ω
    3. Reconnect the shift actuator ECU (shift control actuator assembly) connector.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    GO TO PROBLEM SYMPTOMS TABLE. Refer to  PROBLEM SYMPTOMS TABLE [09/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (SHIFT ACTUATOR ECU - BODY GROUND) 

  7. CHECK HARNESS AND CONNECTOR (SHIFT CONTROL ECU - NO. 2 ENGINE ROOM RELAY BLOCK AND NO. 2 JUNCTION BLOCK ASSEMBLY) 
    1. Remove the P CON MAIN fuse from the No. 2 engine room relay block and No. 2 junction block assembly.
    2. Disconnect the C64 shift actuator ECU (shift control actuator assembly) connector.
    3. Disconnect the D25 shift control ECU (transmission floor shift assembly) connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      D25-2 (BATT) - 2 (P CON MAIN fuse holder) Always Below 1 Ω
      D25-2 (BATT) or 2 (P CON MAIN fuse holder) - Body ground and other terminals Always 10 kΩ or higher
    5. Reconnect the shift control ECU (transmission floor shift assembly) connector.
    6. Reconnect the shift actuator ECU (shift control actuator assembly) connector.
    7. Install the P CON MAIN fuse.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - NO. 1 ENGINE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY) 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (SHIFT CONTROL ECU - NO. 1 ENGINE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY) 

  8. CHECK HARNESS AND CONNECTOR (SHIFT CONTROL ECU - NO. 2 ENGINE ROOM RELAY BLOCK AND NO. 2 JUNCTION BLOCK ASSEMBLY) 
    1. Remove the IGCT NO. 3 fuse from the No. 2 engine room relay block and No. 2 junction block assembly.
    2. Remove the ECU-IGP NO. 3 fuse from the No. 2 engine room relay block and No. 2 junction block assembly.
    3. Disconnect the C53 shift actuator ECU (shift control actuator assembly) connector.
    4. Disconnect the D25 shift control ECU (transmission floor shift assembly) connector.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      D25-3 (IGCT) - 2 (IGCT NO. 3 fuse holder) Always Below 1 Ω
      D25-1 (IGP) - 2 (ECU-IGP NO. 3 fuse holder) Always Below 1 Ω
      D25-3 (IGCT) or 2 (IGCT NO. 3 fuse holder) - Body ground and other terminals Always 10 kΩ or higher
      D25-1 (IGP) or 2 (ECU-IGP NO. 3 fuse holder) - Body ground and other terminals Always 10 kΩ or higher
    6. Reconnect the shift control ECU (transmission floor shift assembly) connector.
    7. Reconnect the shift actuator ECU (shift control actuator assembly) connector.
    8. Install the ECU-IGP NO. 3 fuse.
    9. Install the IGCT NO. 3 fuse.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IGCT NO. 1 RELAY POWER SUPPLY, IGP NO. 1 RELAY POWER SUPPLY) 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (SHIFT CONTROL ECU - NO. 1 ENGINE ROOM RELAY BLOCK AND NO. 1 JUNCTION BLOCK ASSEMBLY) 

  9. CHECK HARNESS AND CONNECTOR (SHIFT ACTUATOR ECU - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY) 
    1. Remove the P CON MTR fuse from the No. 1 engine room relay block and No. 1 junction block assembly.
    2. Remove the P CON MAIN fuse from the No. 2 engine room relay block and No. 2 junction block assembly.
    3. Disconnect the D25 shift control ECU (transmission floor shift assembly) connector.
    4. Disconnect the C53 and C64 shift actuator ECU (shift control actuator assembly) connectors.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      C53-1 (MA1) - 2 (P CON MTR fuse holder) Always Below 1 Ω
      C64-8 (BAT1) - 2 (P CON MAIN fuse holder) Always Below 1 Ω
      C53-1 (MA1) or 2 (P CON MTR fuse holder) - Body ground and other terminals Always 10 kΩ or higher
      C64-8 (BAT1) or 2 (P CON MAIN fuse holder) - Body ground and other terminals Always 10 kΩ or higher
    6. Reconnect the shift actuator ECU (shift control actuator assembly) connector.
    7. Reconnect the shift control ECU (transmission floor shift assembly) connector.
    8. Install the P CON MAIN fuse.
    9. Install the P CON MTR fuse.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY) 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (SHIFT ACTUATOR ECU - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY) 

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