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Home >> Lexus >> 2007 >> GS 430 >> Repair and Diagnosis >> Accessories & Equipment >> Cruise Control Systems >> Cruise Control >> Cruise Control System >> DTC P0571 Brake Switch "A" Circuit >> Inspection Procedure

Inspection Procedure

  1. READ VALUE OF INTELLIGENT TESTER 
    1. Connect the intelligent tester to the DLC3.
    2. Turn the engine switch on (IG), and turn the intelligent tester main switch ON.
    3. Check the DATA LIST for proper functioning of the stop light switch.

    ECM (Cruise control): 

    DIAGNOSTIC NOTE CHART

    Item Measurement Item / Display (Range) Normal Condition Diagnostic Note
    STP LIGHT SW M Stop light switch signal (Main CPU) / ON or OFF ON: Brake pedal depressed
    OFF: Brake pedal released    		 -

    OK: 

    When brake pedal operation is performed, the results will be same as above. 

    OK: REPLACE ECM 

    NG: Go to next step 

  2. INSPECT STOP LIGHT SWITCH 
    1. Disconnect the stop light switch connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Switch Condition Specified Condition
      1 - 2 Switch pin not pushed Below 1 Ω
      3 - 4 Switch pin not pushed 10 kΩ or higher
      1 - 2 Switch pin pushed 10 kΩ or higher
      3 - 4 Switch pin pushed Below 1 Ω
    Fig 1: Inspecting Stop Light Switch
    G05298633Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE STOP LIGHT SWITCH 

    OK: Go to next step 

  3. CHECK WIRE HARNESS (STOP LIGHT SWITCH - BATTERY) 
    1. Measure the voltage according to the value(s) in the table below.

      Standard voltage 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      A35-2 - Body ground Always 10 to 14 V
      A35-3 - Body ground Engine switch on (IG) 10 to 14 V
    Fig 2: Identifying A35 Connector Terminals
    G05298634Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE WIRE HARNESS AND CONNECTOR 

    OK: Go to next step 

  4. CHECK ECM 
    1. Reconnect the stop light switch connector.
    2. Disconnect the A6 and A7 connectors from the ECM.
    3. Turn the engine switch on (IG).
    4. Measure the voltage according to the value(s) in the table below.

      Standard voltage 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Brake Pedal Condition Condition
      A7-4 (STP) - Body ground Depressed 10 to 14 V
      A7-4 (STP) - Body ground Released Below 1 V
      A6-8 (ST1-) - Body ground Depressed Below 1 V
      A6-8 (ST1-) - Body ground Released 10 to 14 V
    Fig 3: Disconnecting A6 And A7 Connectors From ECM
    G05298635Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE WIRE HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM) 

    OK: REPLACE ECM 

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