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Home >> Lexus >> 2024 >> RX 500h >> Repair and Diagnosis >> External Pages >> Different car >> Section 23 (Hybrid Control System - Diagnostic Codes (1 Of 7)) >> HYBRID CONTROL SYSTEM (for PHEV Model) >> DTC P0504-2B: Brake Switch "A"/"B" Signal Cross Coupled [08/2023 - ] >> Procedure

DTC P0504-2B: Brake Switch "A"/"B" Signal Cross Coupled [08/2023 - ]: Procedure

WARNING: This page is about a different car, the 2025 Lexus RX 450h+ and 2024 Lexus RX 450h+. 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) 

    Pre-procedure1

    • Disconnect the stop light switch assembly connector.
    • Measure the voltage according to the value(s) in the table below.
      GTY1206133Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Stop Light Switch Assembly)

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      A32-1 (B) - Body ground Always 11 to 14 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Connect 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) 

    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.
      GTY1206148Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Stop Light Switch Assembly)

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      A32-5 (B) - Body ground Ignition switch ON 11 to 14 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Turn the ignition switch off.
    • Connect 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.
      GTY1206149Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Stop Light Switch Assembly)

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      A32-3 (GND) - Body ground Always Below 1 Ω Ω

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Connect the stop light switch assembly connector.

    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 connector.
    • Turn the ignition switch to ON.
    • Measure the voltage according to the value(s) in the table below.
      GTY1205211Courtesy 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)      		 - -

      Standard Voltage

      Tester Connection Brake Pedal Operation Specified Condition Result
      A21-7 (ST1-) - Body ground Released 7.5 to 14 V V
      A21-7 (ST1-) - Body ground Depressed Below 1.5 V V
      A21-22 (STP) - Body ground Released 7.5 to 14 V V
      A21-22 (STP) - Body ground Depressed Below 1.5 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • Connect the hybrid vehicle control ECU connector.

    Result: 

    OK 

    REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY. Refer to  REMOVAL [10/2022 - ] 

    Result: 

    NG 

    See step  5

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

    Pre-procedure1

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

      Standard Resistance

      Tester Connection Condition Specified Condition Result
      A21-7 (ST1-) - A32-4 (L) Always Below 1 Ω Ω
      A21-22 (STP) - A32-2 (L) Always Below 1 Ω Ω
      A21-7 (ST1-) or A32-4 (L) - Body ground and other terminals Always 10 kΩ or higher kΩ
      A21-22 (STP) or A32-2 (L) - Body ground and other terminals Always 10 kΩ or higher kΩ

      Result

      Proceed to
      OK
      NG

    Post-procedure1

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

    Result: 

    OK 

    REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [10/2022 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  6. CHECK HARNESS AND CONNECTOR (IGP NO. 1 RELAY - HYBRID VEHICLE CONTROL ECU) 

    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) - A32-5 (B) Always Below 1 Ω Ω
      5(IGP NO. 1 relay holder) or A32-5 (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 

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

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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