DYNAMIC RADAR CRUISE CONTROL SYSTEM, Diagnostic DTC:P0571

DTC Code DTC Name
P0571 Stop Light Switch Circuit Malfunction

DESCRIPTION

The ECM receives the brake demand signal from the stop light switch and transmits it to the master cylinder solenoid (skid control ECU). The master cylinder solenoid (skid control ECU) receives the signal from the ECM and operates the brake actuator. When the brake pedal is depressed, the stop light switch sends a signal to the ECM. When the ECM receives this signal, it cancels the cruise control. The fail-safe function operates to enable normal driving even if there is a malfunction in the stop light signal circuit. The cancellation condition occurs when voltage is applied to terminal STP. When the brake is applied, voltage is applied to terminal STP of the ECM through the STOP fuse and the stop light switch, and the ECM turns the cruise control off.

DTC Code DTC Detection Condition Trouble Area
P0571

  • This trouble code is output when the ECM detects the brake light relay error signal from the master cylinder solenoid (skid control ECU) for 0.2 seconds. or more while the dynamic radar cruise control is in operation.

  • When the voltage of the STP terminal and the ST1- terminal of the ECM is below than 1 V for 0.5 seconds. or more.

  • Fuse (STOP, IGN, ECU-IG No. 2)

  • Stop light switch

  • Brake light relay

  • Stop light control relay

  • Master cylinder solenoid (skid control ECU)

  • Harness or connector

  • ECM

WIRING DIAGRAM

A015C49E06

INSPECTION PROCEDURE

PROCEDURE


  1. INSPECT FUSE (STOP, IGN, ECU-IG No. 2)


    1. Remove the STOP and IGN fuses from the engine room relay block.

    2. Remove the ECU-IG No. 2 fuse from the cowl side junction block LH.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      STOP fuse Always Below 1 Ω
      IGN fuse
      ECU-IG No. 2 fuse

    NG

    REPLACE FUSE

    OK

  2. READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH)


    1. Using the intelligent tester, read the Data List Click here.

      Radar Cruise
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light SW M-CPU

      Stop light switch signal (Main CPU) /

      ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

      		 -
      OK
      Normal conditions listed above are displayed.

    NG

    INSPECT STOP LIGHT SWITCH Click here

    OK

  3. INSPECT BRAKE LIGHT RELAY (BRK LP)


    1. A015DGNE01

      Remove the brake light relay from the engine room relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3 - 4 Battery voltage is applied to terminals 1 and 2 10 kΩ higher
      Battery voltage is not applied to terminals 1 and 2 Below 1 Ω
      3 - 5 Battery voltage is not applied to terminals 1 and 2 10 kΩ higher
      Battery voltage is applied to terminals 1 and 2 Below 1 Ω

    NG

    REPLACE BRAKE LIGHT RELAY

    OK

  4. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - BATTERY AND BODY GROUND)


    1. A01558YE01

      Disconnect the A39 stop light control relay connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A39-6 (+B) - Body ground Always 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A39-4 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - STOP LIGHT SWITCH)


    1. A015D46E01

      Disconnect the A39 stop light control relay connector.

    2. Disconnect the A30 stop light switch connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A30-1 - A39-2 (STP) Always Below 1 Ω
      A30-1 - Body ground Always 10 kΩ higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - BRAKE LIGHT RELAY)


    1. A0156CJE02

      Disconnect the A39 stop light control relay connector.

    2. Remove the brake light relay from the engine room relay block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A39-8 (OUT) - Brake light relay terminal 4 Always Below 1 Ω
      A39-8 (OUT) - Body ground Always 10 kΩ higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK STOP LIGHT CONTROL RELAY


    1. A015CPVE02

      Remove the stop light control relay with its connector still connected Click here.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A39-6 (+B) - A39-4 (GND) Always 11 to 14 V
      A39-2 (STP) - Body ground

      Stop light switch on

      (Brake pedal depressed)

      		 11 to 14 V

      Stop light switch off

      (Brake pedal released)

      		 Below 1 V
      A39-8 (OUT) - Body ground

      Stop light switch on

      (Brake pedal depressed)

      		 11 to 14 V

      Stop light switch off

      (Brake pedal released)

      		 Below 1 V

    NG

    REPLACE STOP LIGHT CONTROL RELAY Click here

    OK

  8. CHECK HARNESS AND CONNECTOR (BRAKE LIGHT RELAY - BATTERY)


    1. A015C0VE02

      Remove the brake light relay from the engine room relay block.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      Brake light relay terminal 1 - Body ground Engine switch on (IG) 11 to 14 V
      Brake light relay terminal 5 - Body ground Always

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  9. CHECK HARNESS AND CONNECTOR (BRAKE LIGHT RELAY, STOP LIGHT CONTROL RELAY - MASTER CYLINDER SOLENOID)


    1. A0159OVE02

      Disconnect the A24 master cylinder solenoid (skid control ECU) connector.

    2. Remove the brake light relay from the engine room relay block.

    3. Disconnect the A39 stop light control relay connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Brake light relay terminal 2 - A24-16 (STP0) Always Below 1 Ω
      A39-2 (STP) - A24-45 (STP2)
      Brake light relay terminal 3 - A24-7 (STP)
      Brake light relay terminal 2 - Body ground Always 10 kΩ higher
      A39-2 (STP) - Body ground
      Brake light relay terminal 3 - Body ground
      Result
      Result Proceed to

      OK

      (for LHD)

      		 A

      OK

      (for RHD)

      		 B
      NG C

    B

    REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

    REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) Click here

  10. INSPECT STOP LIGHT SWITCH


    1. A015DAHE01

      Remove the stop light switch Click here.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      1 - 2 Pin not pushed Below 1 Ω
      Pin pushed 10 kΩ higher
      3 - 4 Pin not pushed 10 kΩ higher
      Pin pushed Below 1 Ω

    NG

    REPLACE STOP LIGHT SWITCH Click here

    OK

  11. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - BATTERY)


    1. A015ANRE01

      Disconnect the A30 stop light switch connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A30-2 - Body ground Engine switch on (IG) 11 to 14 V
      A30-4 - Body ground Always

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  12. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)


    1. A01580DE02

      Disconnect the A38*1 or A53*2 ECM connector.


      • *1: for LHD

      • *2: for RHD

    2. Disconnect the A30 stop light switch connector.

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

      Standard Resistance
      for LHD
      Tester Connection Condition Specified Condition
      A30-3 - A38-35 (ST1-) Always Below 1 Ω
      A30-1 - A38-36 (STP)
      A30-1 - Body ground Always 10 kΩ higher
      A30-3 - Body ground
      for RHD
      Tester Connection Condition Specified Condition
      A30-3 - A53-35 (ST1-) Always Below 1 Ω
      A30-1 - A53-36 (STP)
      A30-1 - Body ground Always 10 kΩ higher
      A30-3 - Body ground
      Result
      Result Proceed to
      OK (1UR-FE) A
      OK (3UR-FE) B
      NG C

    B

    REPLACE ECM Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

    REPLACE ECM Click here