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Home >> Lexus >> 2024 >> TX 350 Base, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 83 (Hybrid Control System - Diagnostic Codes (1 Of 5)) >> HYBRID CONTROL SYSTEM (for 1Motor-HEV Model) >> DTC P0504-2B: Brake Switch "A"/"B" Signal Cross Coupled [09/2023 - ] >> Procedure

DTC P0504-2B: Brake Switch "A"/"B" Signal Cross Coupled [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 TERMINAL VOLTAGE (POWER SOURCE OF STOP LIGHT SWITCH ASSEMBLY) 
    GTY1232952Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Stop Light Switch Assembly)

    Pre-procedure1

    • Disconnect the stop light switch assembly connector.
    • Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      B33-1 (B) - Body ground Always 11 to 14 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the stop light switch assembly connector.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE OF STOP LIGHT SWITCH ASSEMBLY) 

    Result: 

    OK 

    See step  2

  2. CHECK TERMINAL VOLTAGE (POWER SOURCE OF STOP LIGHT SWITCH ASSEMBLY) 
    GTY1232953Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Front view of wire harness connector
    (to Stop Light Switch Assembly)

    Pre-procedure1

    • Disconnect the stop light switch assembly connector.
    • 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
      B33-5 (B) - Body ground Ignition switch ON 11 to 14 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Turn the ignition switch off.
    • Reconnect the stop light switch assembly connector.

    Result: 

    NG 

    See step  6

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BODY GROUND) 

    Pre-procedure1

    • Disconnect the stop light switch assembly connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      B33-3 (GND) - Body ground Always Below 1 Ω Ω
      GTY1232956Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Stop Light Switch Assembly)

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None.

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. CHECK TERMINAL VOLTAGE (STP, ST1-VOLTAGE) 

    Pre-procedure1

    • Disconnect the hybrid vehicle control ECU assembly connector.
    • Turn the ignition switch to ON.
    • Measure the voltage according to the value(s) in the table below.
      GTY1238221Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Brake Pedal Depressed *b Brake Pedal Released
      *c Front view of wire harness connector
      (to Hybrid Vehicle Control ECU Assembly)      		 - -

      Standard Voltage

      Tester Connection Brake Pedal Operation Specified Condition Result
      B21-7 (ST1-) - Body ground Released 7.5 to 14 V V
      B21-7 (ST1-) - Body ground Depressed Below 1.5 V V
      B21-22 (STP) - Body ground Released Below 1.5 V V
      B21-22 (STP) - Body ground Depressed 7.5 to 14 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the hybrid vehicle control ECU assembly connector.

    Result: 

    OK 

    REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY. Refer to  REMOVAL [09/2023 - 12/2023]  , or refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU ASSEMBLY - STOP LIGHT SWITCH ASSEMBLY) 

    Pre-procedure1

    • Disconnect the hybrid vehicle control ECU assembly connector.
    • Disconnect the stop light switch assembly connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      B21-7 (ST1-) - B33-4 (L) Always Below 1 Ω Ω
      B21-22 (STP) - B33-2 (L) Always Below 1 Ω Ω
      B21-7 (ST1-) or B33-4 (L) - Body ground and other terminals Always 10 kΩ or higher kΩ
      B21-22 (STP) or B33-2 (L) - Body ground and other terminals Always 10 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the stop light switch assembly connector.
    • Reconnect the hybrid vehicle control ECU assembly connector.

    Result: 

    OK 

    REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [09/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  6. CHECK HARNESS AND CONNECTOR (IGP NO. 1 RELAY - STOP LIGHT SWITCH ASSEMBLY) 

    Pre-procedure1

    • Remove the IGP NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.
    • Disconnect the stop light switch assembly connector.
    • Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      5 (IGP NO. 1 relay holder) - B33-5 (B) Always Below 1 Ω Ω
      5 (IGP NO. 1 relay holder) or B33-5 (B) - Body ground and other terminals Always 10 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Reconnect the stop light switch assembly connector.
    • Install the IGP NO. 1 relay.

    Result: 

    OK 

    CHECK ECU POWER SOURCE CIRCUIT. Refer to  ECU Power Source Circuit [09/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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