CRUISE CONTROL SYSTEM (for 1WW), Diagnostic DTC:C1A05

DTC Code DTC Name
C1A05 Stop Light Switch Circuit

DESCRIPTION

When the brake pedal is depressed, the stop light switch assembly sends a brake pedal operation signal to the driving support ECU. After reception of this signal, the driving support ECU cancels the radar cruise control system. When the driving support ECU detects a problem in the stop light switch circuit, DTC C1A05 is stored.

DTC Code DTC Detection Condition Trouble Area
C1A05 The voltages of terminals ST1- and STP of the driving support ECU are both below 1 V for 0.5 seconds or more.

  • Stop light switch assembly

  • Driving support ECU

  • Harness or connector (stop light signal circuit)

WIRING DIAGRAM

A01IQ18E01

INSPECTION PROCEDURE

Note


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

  • When replacing the driving support ECU, always replace it with a new one. If a driving support ECU which was installed to another vehicle is used, the information stored in the driving support ECU will not match the information from the vehicle. As a result, a DTC may be stored.

PROCEDURE


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


    1. A01IQ65E02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the stop light switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A55-2 (GND) - Body ground Always Below 1 Ω

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A55-6 (B) - Body ground Ignition switch ON 11 to 14 V
      Ignition switch off Below 1 V
      A55-7 (B) - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - DRIVING SUPPORT ECU)


    1. Disconnect the A55 stop light switch assembly connector.

    2. Disconnect the H124 driving support ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A55-5 (L) - H124-28 (ST1-) Always Below 1 Ω
      A55-3 (L) - H124-27 (STP-)
      A55-5 (L) or H124-28 (ST1-) - Body ground Always 10 kΩ or higher
      A55-3 (L) or H124-27 (STP-) - Body ground

    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 DTCs Click here.

    3. Check for the DTCs Click here.

      OK
      DTC C1A05 is not output.
      Result
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

    B

    REPLACE DRIVING SUPPORT ECU Click here

    C

    REPLACE DRIVING SUPPORT ECU Click here

    A

    END (STOP LIGHT SWITCH ASSEMBLY WAS DEFECTIVE)