LANE-KEEPING ASSIST SYSTEM, 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

  1. Diagnosis condition for each system:


    • Radar cruise control system:


      • ACC main switch is on


    • Lane keeping assist system:


      • Lane-keeping assist main switch is on

  2. Driving support ECU detects malfunction* in signal from stop light switch assembly

    *: Signal is determined to be malfunctioning when ST1- signal and STP signal do not match

  • Stop light switch assembly

  • Driving support ECU

  • Lighting system

  • Harness or connector (stop light signal circuit)

WIRING DIAGRAM

A01FIL3E02

INSPECTION PROCEDURE

Note

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

PROCEDURE


  1. CHECK STOP LIGHT OPERATION


    1. Turn the engine switch on (IG), depress the brake pedal and check that the stop lights illuminate.

      OK
      The stop lights illuminate when the brake pedal is depressed and turn off when the brake pedal is released.

    NG

    GO TO LIGHTING SYSTEM Click here

    OK

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


    1. Disconnect the A5 stop light switch assembly connector.

    2. Disconnect the N5 driving support ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A5-2 (L) - N5-27 (STP-) Always Below 1 Ω
      A5-4 (L) - N5-28 (ST1-) Always Below 1 Ω
      A5-2 (L) - Body ground Always 10 kΩ or higher
      A5-4 (L) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. REPLACE STOP LIGHT SWITCH ASSEMBLY


    1. Replace the stop light switch assembly Click here.


    NEXT

  4. CHECK FOR DTC (SFI SYSTEM)


    1. Clear the DTCs.

      for 2GR-FSE Click here

      for 4GR-FSE Click here

    2. Make sure the following conditions are met:

      Tech Tips

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


      • Radar cruise control system:

        The vehicle is being driven at a speed of approximately 50 km/h (31 mph) or more and the ACC main switch is on.

      • Lane keeping assist system:

        The vehicle is being driven at a speed of approximately 50 km/h (31 mph) or more and the lane-keeping assist main switch is on.

      • The brake pedal is depressed for 1 second or more.

    3. Check for DTCs.

      for 2GR-FSE Click here

      for 4GR-FSE Click here

      OK
      DTC P0504 is not output.
      Result
      Result Proceed to
      OK A
      NG (for 2GR-FSE) B
      NG (for 4GR-FSE) C

    B

    GO TO SFI SYSTEM Click here

    C

    GO TO SFI SYSTEM Click here

    A

  5. CHECK FOR DTC


    1. Check for DTCs Click here.

      OK
      DTC C1A05 is not output.

      Note

      When replacing the driving support ECU, always replace it with a new one and be sure to perform initialization Click here. If an ECU which was installed to another vehicle is used, the information stored in the ECU will not match the information from the vehicle, and as a result, a DTC may be stored.


    NG

    REPLACE DRIVING SUPPORT ECU Click here

    OK

    END (STOP LIGHT SWITCH ASSEMBLY IS DEFECTIVE)