CRUISE CONTROL SYSTEM, Diagnostic DTC:P0571

DTC Code DTC Name
P0571 Stop Light Switch Circuit Malfunction

DESCRIPTION

When the brake pedal is depressed, the stop light switch sends a signal to the hybrid vehicle control ECU.

Upon receiving the signal, the hybrid vehicle control ECU cancels the cruise control system. Even if there is a malfunction in the stop light signal circuit while the cruise control is in operation, normal driving is maintained due to a fail-safe function. Cruise control is canceled when positive auxiliary battery voltage is applied to terminal STP.

When the brake pedal is depressed, positive voltage is applied to terminal STP of the hybrid vehicle control ECU through the STOP fuse and the stop light switch, and the hybrid vehicle control ECU cancels the cruise control.

When the brake pedal is released, positive voltage is applied to terminal ST1- of the hybrid vehicle control ECU through the ECU-IG fuse and the stop light switch, and the hybrid vehicle control ECU operates the cruise control.

DTC Code DTC Detection Condition Trouble Area
P0571 Trouble code is output when voltages of terminals ST1- and STP of hybrid vehicle control ECU are both below 1 V for 0.5 sec. or more

  • Stop light switch

  • Stop light switch circuit

  • Hybrid vehicle control ECU

WIRING DIAGRAM

A01GX2AE04

INSPECTION PROCEDURE

Note

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

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - AUXILIARY BATTERY AND BODY GROUND)


    1. A01H06AE05

      Disconnect the A95 stop light switch assembly connector.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      A95-1 (B) - Body ground Always 11 to 14 V
      A95-5 (B) - Body ground Power switch ON (IG) 11 to 14 V

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

      Standard resistance
      Tester Connection Condition Specified Condition
      A95-3 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the A77 and A78 hybrid vehicle control ECU connectors.

      A01H2BME02

    2. Disconnect the A95 stop light switch assembly connector.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      A77-1 (STP) - A95-2 (L) Always Below 1 Ω
      A78-6 (ST1-) - A95-4 (L) Always Below 1 Ω
      A77-1 (STP) - Body ground Always 10 kΩ or higher
      A78-6 (ST1-) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK STOP LIGHT SWITCH ASSEMBLY


    1. Temporarily replace the stop light switch assembly with a new or normally functioning one Click here.

    2. Clear the DTC Click here.

    3. Recheck for the DTC Click here.

      OK
      DTC P0571 is not output.

    NG

    REPLACE HYBRID VEHICLE CONTROL ECU Click here

    OK

    END (STOP LIGHT SWITCH ASSEMBLY IS DEFECTIVE)