LEMON Manuals: Even more car manuals for everyone
Home >> Lexus >> 2025 >> NX 350h >> Repair and Diagnosis >> External Pages >> Different car >> Section 59 (Smart Access System (For Start) - Diagnostic Codes & Symptom Tests (1 Of 2)) >> SMART ACCESS SYSTEM WITH PUSH-BUTTON START (for Start Function, Gasoline Model) >> DTC B2278-62: Engine/Power Switch Signal Compare Failure [11/2021 - ] >> Procedure

DTC B2278-62: Engine/Power Switch Signal Compare Failure [11/2021 - ]: Procedure

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2025 Lexus NX 350, 2025 Lexus NX 250, 2024 Lexus NX 350, 2024 Lexus NX 250, and 2023 Lexus NX 350. However, it is still accessible from the selected car via links, so may be relevant.
  1. READ VALUE USING GTS (PUSH START SWITCH 1) 
    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
      Push Start Switch 1 Engine switch 1 status OFF or ON OFF: Engine switch not pressed
      • If the engine switch is pressed for a short time, the display may not change.
      • Use this item to determine if the engine switch input signal is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Push Start Switch 1

      OK

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

      Result

      Result Proceed to
      The value of Push Start Switch 1 is OFF A
      The value of Push Start Switch 1 is not OFF B

    Result: 

    B 

    See step  13

    Result: 

    A 

    See step  2

  2. READ VALUE USING GTS (PUSH START SWITCH 1) 
    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
      Push Start Switch 1 Engine switch 1 status OFF or ON ON: Engine switch pressed
      • If the engine switch is pressed for a short time, the display may not change.
      • Use this item to determine if the engine switch input signal is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Push Start Switch 1

      OK

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

      Result

      Result Proceed to
      The value of Push Start Switch 1 is ON A
      The value of Push Start Switch 1 is not ON B

    Result: 

    B 

    See step  13

    Result: 

    A 

    See step  3

  3. READ VALUE USING GTS (PUSH START SWITCH 2) 
    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
      Push Start Switch 2 Engine switch 2 status OFF or ON OFF: Engine switch not pressed
      • If the engine switch is pressed for a short time, the display may not change.
      • Use this item to determine if the engine switch input signal is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Push Start Switch 2

      OK

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

      Result

      Result Proceed to
      The value of Push Start Switch 2 is OFF A
      The value of Push Start Switch 2 is not OFF B

    Result: 

    B 

    See step  13

    Result: 

    A 

    See step  4

  4. READ VALUE USING GTS (PUSH START SWITCH 2) 
    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
      Push Start Switch 2 Engine switch 2 status OFF or ON ON: Engine switch pressed
      • If the engine switch is pressed for a short time, the display may not change.
      • Use this item to determine if the engine switch input signal is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Push Start Switch 2

      OK

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

      Result

      Result Proceed to
      The value of Push Start Switch 2 is ON A
      The value of Push Start Switch 2 is not ON B

    Result: 

    B 

    See step  13

    Result: 

    A 

    See step  5

  5. READ VALUE USING GTS (PUSH START SWITCH 3) 
    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
      Push Start Switch 3 Engine switch 3 status OFF or ON OFF: Engine switch not pressed
      • If the engine switch is pressed for a short time, the display may not change.
      • Use this item to determine if the engine switch input signal is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Push Start Switch 3

      OK

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

      Result

      Result Proceed to
      The value of Push Start Switch 3 is OFF A
      The value of Push Start Switch 3 is not OFF B

    Result: 

    B 

    See step  13

    Result: 

    A 

    See step  6

  6. READ VALUE USING GTS (PUSH START SWITCH 3) 
    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
      Push Start Switch 3 Engine switch 3 status OFF or ON ON: Engine switch pressed
      • If the engine switch is pressed for a short time, the display may not change.
      • Use this item to determine if the engine switch input signal is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Push Start Switch 3

      OK

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

      Result

      Result Proceed to
      The value of Push Start Switch 3 is ON A
      The value of Push Start Switch 3 is not ON B

    Result: 

    B 

    See step  13

    Result: 

    A 

    See step  7

  7. READ VALUE USING GTS (PUSH START SWITCH 1) 
    1. According to the display on the GTS, read the Data List while wiggling the wire harness.

      Body Electrical > Power Source Control > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Push Start Switch 1 Engine switch 1 status OFF or ON OFF: Engine switch not pressed
      • If the engine switch is pressed for a short time, the display may not change.
      • Use this item to determine if the engine switch input signal is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Push Start Switch 1

      OK

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

      Result

      Result Proceed to
      The value of Push Start Switch 1 is OFF A
      The value of Push Start Switch 1 is not OFF B

    Result: 

    B 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    A 

    See step  8

  8. READ VALUE USING GTS (PUSH START SWITCH 1) 
    1. According to the display on the GTS, read the Data List while wiggling the wire harness.

      Body Electrical > Power Source Control > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Push Start Switch 1 Engine switch 1 status OFF or ON ON: Engine switch pressed
      • If the engine switch is pressed for a short time, the display may not change.
      • Use this item to determine if the engine switch input signal is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Push Start Switch 1

      OK

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

      Result

      Result Proceed to
      The value of Push Start Switch 1 is ON A
      The value of Push Start Switch 1 is not ON B

    Result: 

    B 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    A 

    See step  9

  9. READ VALUE USING GTS (PUSH START SWITCH 2) 
    1. According to the display on the GTS, read the Data List while wiggling the wire harness.

      Body Electrical > Power Source Control > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Push Start Switch 2 Engine switch 2 status OFF or ON OFF: Engine switch not pressed
      • If the engine switch is pressed for a short time, the display may not change.
      • Use this item to determine if the engine switch input signal is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Push Start Switch 2

      OK

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

      Result

      Result Proceed to
      The value of Push Start Switch 2 is OFF A
      The value of Push Start Switch 2 is not OFF B

    Result: 

    B 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    A 

    See step  10

  10. READ VALUE USING GTS (PUSH START SWITCH 2) 
    1. According to the display on the GTS, read the Data List while wiggling the wire harness.

      Body Electrical > Power Source Control > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Push Start Switch 2 Engine switch 2 status OFF or ON ON: Engine switch pressed
      • If the engine switch is pressed for a short time, the display may not change.
      • Use this item to determine if the engine switch input signal is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Push Start Switch 2

      OK

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

      Result

      Result Proceed to
      The value of Push Start Switch 2 is ON A
      The value of Push Start Switch 2 is not ON B

    Result: 

    B 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    A 

    See step  11

  11. READ VALUE USING GTS (PUSH START SWITCH 3) 
    1. According to the display on the GTS, read the Data List while wiggling the wire harness.

      Body Electrical > Power Source Control > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Push Start Switch 3 Engine switch 3 status OFF or ON OFF: Engine switch not pressed
      • If the engine switch is pressed for a short time, the display may not change.
      • Use this item to determine if the engine switch input signal is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Push Start Switch 3

      OK

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

      Result

      Result Proceed to
      The value of Push Start Switch 3 is OFF A
      The value of Push Start Switch 3 is not OFF B

    Result: 

    B 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    A 

    See step  12

  12. READ VALUE USING GTS (PUSH START SWITCH 3) 
    1. According to the display on the GTS, read the Data List while wiggling the wire harness.

      Body Electrical > Power Source Control > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Push Start Switch 3 Engine switch 3 status OFF or ON ON: Engine switch pressed
      • If the engine switch is pressed for a short time, the display may not change.
      • Use this item to determine if the engine switch input signal is malfunctioning.

      Body Electrical > Power Source Control > Data List 

      Tester Display
      Push Start Switch 3

      OK

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

      Result

      Result Proceed to
      The value of Push Start Switch 3 is ON A
      The value of Push Start Switch 3 is not ON B

    Result: 

    A 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - ] 

    Result: 

    B 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  13. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - ENGINE SWITCH) 

    Pre-procedure1

    1. Disconnect the D58 certification ECU (smart key ECU assembly) connector.
    2. Disconnect the D59 engine switch connector.

      Procedure1

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      D58-19 (SSW1) - D59-12 (SS1) Always Below 1 Ω
      D58-27 (SSW2) - D59-6 (SS2) Always Below 1 Ω
      D58-23 (SSW3) - D59-11 (SS3) Always Below 1 Ω
      D58-30 (AGND) - D59-3 (AGND) Always Below 1 Ω
      D58-19 (SSW1) or D59-12 (SS1) - Other terminals and body ground Always 10 kΩ or higher
      D58-27 (SSW2) or D59-6 (SS2) - Other terminals and body ground Always 10 kΩ or higher
      D58-23 (SSW3) or D59-11 (SS3) - Other terminals and body ground Always 10 kΩ or higher
      D58-30 (AGND) or D59-3 (AGND) - Other terminals and body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    4. None

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  14

  14. INSPECT ENGINE SWITCH 

    for A25A-FKS: Refer to INSPECTION [11/2021 - ]

    for T24A-FTS: Refer to 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 ENGINE SWITCH 

    for A25A-FKS: Refer to REMOVAL [11/2021 - ]

    for T24A-FTS: Refer to REMOVAL [11/2021 - ]

scientia non olet · About LEMON Manuals