DYNAMIC RADAR CRUISE CONTROL SYSTEM, Diagnostic DTC:P0571

DTC Code DTC Name
P0571 Brake Switch "A" Circuit

DESCRIPTION


DTC No. DTC Detection Condition Trouble Area
P0571 When the power switch is on (IG) and the dynamic radar cruise control system is operating, voltage of STP terminal and that of ST1- terminal of hybrid vehicle control ECU assembly are less than 1 V for approximately 0.5 seconds or more.

  • Stop light switch assembly

  • Stop light switch circuit

  • Hybrid vehicle control ECU assembly
While the dynamic radar cruise control system is operating (vehicle-to-vehicle distance control mode), the hybrid vehicle control ECU assembly detects the No. 1 integration relay error signal from the skid control ECU (brake booster with master cylinder assembly) for approximately 0.2 seconds or more.

  • No. 1 integration relay

  • No. 1 integration relay circuit

  • Skid control ECU (brake booster with master cylinder assembly)

  • Hybrid vehicle control ECU assembly

WIRING DIAGRAM

A00094UE03

CAUTION / NOTICE / HINT

Tech Tips

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE


  1. CHECK STOP LIGHT OPERATION


    1. Check that the stop lights come on when the brake pedal is depressed, and go off when the brake pedal is released.

      OK
      Condition Illumination Condition
      Brake pedal depressed ON
      Brake pedal released OFF

    NG

    GO TO LIGHTING SYSTEM (EXT) Click here

    OK

  2. READ VALUE USING GTS (STOP LIGHT SWITCH)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Hybrid Control / Data List.

    5. Check the Data List for proper functioning of the stop light switch.

      Hybrid Control
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light Switch Stop light switch status / ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

      		 -
      OK
      Display changes according to brake pedal operation described in above table.

    6. Turn the power switch off.


    NG

    CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH POWER SOURCE CIRCUIT) Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU)


    1. Disconnect the A28 stop light switch assembly connector.

    2. Disconnect the A24 skid control ECU (brake booster with master cylinder assembly) connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A28-2 (L) - A24-33 (STP) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A28-2 (L) or A24-33 (STP) - Body ground Always 10 kΩ or higher

    4. Reconnect the A24 skid control ECU (brake booster with master cylinder assembly) connector.

    5. Reconnect the A28 stop light switch assembly connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK HARNESS AND CONNECTOR (NO. 1 INTEGRATION RELAY - SKID CONTROL ECU)


    1. Disconnect the 1F and 1G No. 1 integration relay connectors.

    2. Disconnect the A24 skid control ECU (brake booster with master cylinder assembly) connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      1F-11 (STOP) - A24-6 (STP2) Always Below 1 Ω
      1F-16 (STPS) - A24-33 (STP) Always Below 1 Ω
      1G-3 (ACC) - A24-3 (STPO) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      1F-11 (STOP) or A24-6 (STP2) - Body ground Always 10 kΩ or higher
      1F-16 (STPS) or A24-33 (STP) - Body ground Always 10 kΩ or higher
      1G-3 (ACC) or A24-3 (STPO) - Body ground Always 10 kΩ or higher

    4. Reconnect the A24 skid control ECU (brake booster with master cylinder assembly) connector.

    5. Reconnect the 1F and 1G No. 1 integration relay connectors.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. INSPECT NO. 1 INTEGRATION RELAY

    Click here


    NG

    REPLACE NO. 1 INTEGRATION RELAY Click here

    OK

  6. REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

    (See page for LHD, Click here for RHD)


    NEXT

  7. CHECK FOR DTCs (DTC P0571)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Clear the DTCs Click here.

    4. Make sure that the DTC detection conditions are met.

      Tech Tips

      If the detection conditions are not met, the system cannot detect the malfunction.

    5. Enter the following menus: Powertrain / Radar Cruise1 / Trouble Codes.

    6. Check for DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC P0571 is output B

    7. Turn the power switch off.


    A

    END

    B

    REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY Click here

  8. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH POWER SOURCE CIRCUIT)


    1. Disconnect the A28 stop light switch assembly connector.

    2. A0003N8E03
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A28-1 (B) - A28-3 (GND) Power switch off 11 to 14 V
      A28-5 (B) - A28-3 (GND) Power switch on (IG) 11 to 14 V
      Standard Resistance
      Tester Connection Condition Specified Condition
      A28-3 (GND) - Body ground Always Below 1 Ω

    3. Reconnect the A28 stop light switch assembly connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  9. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. A0007HSE03
      Text in Illustration
      *a

      Component with harness connected

      (Stop Light Switch Assembly)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A28-2 (L) - A28-3 (GND) Brake pedal not depressed Below 1 V
      Brake pedal depressed 11 to 14 V
      A28-4 (L) - A28-3 (GND) Power switch on (IG), brake pedal not depressed 11 to 14 V
      Power switch on (IG), brake pedal depressed Below 1 V

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

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


    1. Disconnect the A78 and A79 hybrid vehicle control ECU assembly connectors.

    2. Disconnect the A28 stop light switch assembly connector.

    3. Disconnect the 1F and 1G No. 1 integration relay connectors.

    4. Disconnect the A24 skid control ECU (brake booster with master cylinder assembly) connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A78-15 (STP) - A28-2 (L) Always Below 1 Ω
      A79-28 (ST1-) - A28-4 (L) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A78-15 (STP) or A28-2 (L) - Body ground Always 10 kΩ or higher
      A79-28 (ST1-) or A28-4 (L) - Body ground Always 10 kΩ or higher

    6. Reconnect the A24 skid control ECU (brake booster with master cylinder assembly) connector.

    7. Reconnect the 1F and 1G No. 1 integration relay connectors.

    8. Reconnect the A28 stop light switch assembly connector.

    9. Reconnect the A78 and A79 hybrid vehicle control ECU assembly connectors.


    OK

    REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR