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Home >> Lexus >> 2024 >> NX 250 FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 145 (Smart Access System (For Start) - Symptom Tests (2 Of 2)) >> SMART ACCESS SYSTEM WITH PUSH-BUTTON START (for Start Function, HEV Model) >> Power Source Mode does not Change to ON (READY) [11/2021 - 03/2023] >> Procedure

Power Source Mode does not Change to ON (READY) [11/2021 - 03/2023]: Procedure

WARNING: This page is about a different car, the 2025 Lexus NX 350h, 2024 Lexus NX 350h, 2023 Lexus NX 350h, and 2022 Lexus NX 350h. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK POWER SWITCH CONDITION 
    1. Get into the vehicle while carrying an electrical key transmitter sub-assembly.
    2. Move the shift position to P.
    3. With the brake pedal released, check that pressing the power switch causes the power source mode to change.

      Result

      Result Proceed to
      Power source mode changes: Off → ACC → ON → off A
      Power source mode does not change to ACC or ON B
      Power source mode changes to ON but not to ACC C
      Power source mode changes to ACC but not to ON D

    Result: 

    B 

    GO TO OTHER PROBLEM (Power Source Mode does not Change to ON (IG and ACC)). Refer to  Power Source Mode does not Change to ON (IG and ACC) [11/2021 - ] 

    Result: 

    C 

    GO TO OTHER PROBLEM (Power Source Mode does not Change to ON (ACC)). Refer to  Power Source Mode does not Change to ON (ACC) [11/2021 - ]  

    Result: 

    D 

    GO TO OTHER PROBLEM (Power Source Mode does not Change to ON (IG)). Refer to  Power Source Mode does not Change to ON (IG) [11/2021 - ]  

    Result: 

    A 

    See step  2

  2. READ VALUE USING GTS (STOP LIGHT SWITCH) 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Power Source Control > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Stop Light Switch State of brake pedal OFF or ON OFF: Brake pedal released
      ON: Brake pedal depressed
      • Use this item to determine if the stop light switch assembly is malfunctioning.
      • The hybrid control system cannot be started when this item is OFF.
      • If the stop light switch assembly is malfunctioning, the hybrid control system can be started by pressing and holding the power switch for a certain period of time.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Stop Light Switch

      OK

      The GTS display changes correctly in response to the brake pedal operation.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  7

    Result: 

    OK 

    See step  3

  3. READ VALUE USING GTS (SHIFT P SIGNAL CONDITION LINE (LINE)) 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Power Source Control > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Shift P Signal Condition (Line) Shift position P Shift P, Other than shift P, Shift N or Other than shift P/N Shift P: Shift position in P
      Shift N: Shift position in N
      Other than shift P/N: Other than
      shift position in P or N      		 Use this item to determine if the shift position switch is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Shift P Signal Condition (Line)

      OK

      The GTS display changes correctly in response to the shift position.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  10

    Result: 

    OK 

    See step  4

  4. READ VALUE USING GTS (POWER SUPPLY CONDITION) 
    1. Read the Data List according to the display on the GTS.

      Body Electrical > Power Source Control > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Power Supply Condition Power supply state OFF, ACC ON, IGR ON, IGP ON or Starter ON OFF: Ignition switch off
      ACC ON: Ignition switch ACC
      IGR ON: Ignition switch ON
      IGP ON: Ignition switch ON
      Starter ON: Sending hybrid control system start request signal      		 -

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Power Supply Condition
      NOTE:

      Check that the key indicator display is displayed on the multi-information display in the combination meter assembly, and then press the power switch.

      OK

      The GTS display changes correctly in response to the power switch operation.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  11

    Result: 

    OK 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - HYBRID VEHICLE CONTROL ECU) 
    1. Disconnect the A10 certification ECU (smart key ECU assembly) connector.
    2. Disconnect the D67 hybrid vehicle control ECU connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A10-2 (ST2) - D67-4 (ST2) Always Below 1 Ω
      A10-2 (ST2) or D67-4 (ST2) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  6

  6. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 
    1. Connect the A10 certification ECU (smart key ECU assembly) connector.
    2. Connect the D67 hybrid vehicle control ECU connector.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A10-2 (ST2) - Body ground With the brake pedal depressed, the power switch is pressed and held → After approx. 3 sec. has elapsed, the power switch is released 8.5 V or higher → 1.0 V or less
      GTY1080654Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Certification ECU (Smart Key ECU Assembly))

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    GO TO HYBRID CONTROL SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - ] 

    Result: 

    NG 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [11/2021 - ] 

  7. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - POWER SOURCE AND BODY GROUND) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A37-1 (B) - Body ground Ignition switch off 11 to 14 V
      GTY1059722Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Stop Light Switch Assembly)
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A37-3 (GND) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - STOP LIGHT SWITCH ASSEMBLY) 
    1. Disconnect the A10 certification ECU (smart key ECU assembly) connector.
    2. Disconnect the A27 hybrid vehicle control ECU connector.
    3. Disconnect the A38 No. 2 skid control ECU (brake actuator assembly) connector.
    4. Disconnect the A77 semiconductor power integration ECU connector.
    5. Disconnect the D39 transmission floor shift assembly connector.
    6. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A10-21 (STP1) - A37-2 (L) Always Below 1 Ω
      A10-21 (STP1) or A37-2 (L) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  9

  9. CHECK STOP LIGHT SWITCH ASSEMBLY 
    1. Check the stop light switch assembly.

      Refer to ON-VEHICLE INSPECTION [11/2021 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [11/2021 - ] 

    Result: 

    NG 

    REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [11/2021 - ] 

  10. CHECK TRANSMISSION FLOOR SHIFT ASSEMBLY 
    1. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      D58-14 (P) - Body ground Ignition switch ACC → ignition switch ON and Shift position in P Pulse generation (24 to 25 Hz or 30 to 31 Hz, High voltage: 9 V or more, Low voltage: below 1 V, duty ratio: 25 %)
      Ignition switch ACC → ignition switch ON and Shift position in N Pulse generation (24 to 25 Hz or 30 to 31 Hz, High voltage: 9 V or more, Low voltage: below 1 V, duty ratio: 55 %)
      Ignition switch ACC → ignition switch ON and Shift position in other then P or N Pulse generation (24 to 25 Hz or 30 to 31 Hz, High voltage: 9 V or more, Low voltage: below 1 V, duty ratio: 40 %)
      GTY1081380Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Certification ECU (Smart Key ECU Assembly))

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [11/2021 - ] 

    Result: 

    NG 

    See step  13

  11. CHECK STEERING LOCK FUNCTION 
    1. Check that the steering unlocks when the ignition switch is turned to ACC.

      OK

      The steering unlocks.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    GO TO OTHER PROBLEM (Unable to Unlock Steering Wheel (Hybrid Control System cannot Start)). Refer to  Unable to Unlock Steering Wheel (Hybrid Control System cannot Start) [11/2021 - 03/2023]  

    Result: 

    OK 

    See step  12

  12. CHECK SECURITY INDICATOR LIGHT (IMMOBILIZER FUNCTION UNSET) 
    1. Get into the vehicle while carrying an electrical key transmitter sub-assembly.
    2. Move the shift position to P.
    3. Press the power switch with the brake pedal released and check that the security indicator light changes from blinking to off at the same time that the power source mode changes to ACC.

      OK

      The security indicator light changes from blinking to off at the same time that the power source mode changes to ACC.

      HINT: 

      The immobilizer function can be determined to be operating correctly if the security indicator light changes from blinking to off at the same time that the power source mode changes to ACC.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [11/2021 - ] 

    Result: 

    NG 

    GO TO OTHER PROBLEM (Immobilizer System does not Operate Properly). Refer to  Immobilizer System does not Operate Properly [11/2021 - ]  

  13. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - TRANSMISSION FLOOR SHIFT ASSEMBLY) 
    1. Disconnect the D58 certification ECU (smart key ECU assembly) connector.
    2. Disconnect the D39 transmission floor shift assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      D58-14 (P) - D39-7 (PPOS) Always Below 1 Ω
      D58-14 (P) or D39-7 (PPOS) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE TRANSMISSION FLOOR SHIFT ASSEMBLY. Refer to  DISASSEMBLY [11/2021 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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