VEHICLE STABILITY CONTROL SYSTEM, Diagnostic DTC:C1426

DTC Code DTC Name
C1426 Stop Light Switch OFF Stuck Malfunction

DESCRIPTION

The skid control ECU (brake actuator assembly) receives stop light switch assembly signals and uses them to determine whether or not the brakes are applied.

The skid control ECU (brake actuator assembly) has a detection circuit that it uses to detect a short in the stop light input signal circuit or stop light circuit when the stop light switch assembly is on (brake pedal depressed).

If the skid control ECU (brake actuator assembly) detects a short in this circuit, it will store this DTC.

DTC No. Detection Item DTC Detection Condition Trouble Area
C1426 Stop Light Switch OFF Stuck Malfunction

Either of the following is detected when the vehicle speed of 3 km/h (2 mph) or more:


  1. With the stop light switch assembly off, the stop light switch assembly is judged to be on based on the master cylinder pressure value for 3 seconds or more.

  2. With the stop light switch assembly off, the master cylinder pressure is more than 8 MPa (81.6 kgf/cm2, 1160 psi) for 3 seconds or more.

  • Wire harness or connector

  • Stop light switch assembly

  • Skid Control ECU (brake Actuator Assembly)
DTC Detection Conditions: C1426
Vehicle Condition
Pattern 1 Pattern 2
Diagnosis Condition The vehicle speed of 3 km/h (2 mph) or more. ○ ○
The stop light switch assembly is off. ○ ○
Malfunction Status The stop light switch assembly is judged to be on based on the master cylinder pressure value. ○ -

The master cylinder pressure is more than 8 MPa (81.6 kgf/cm2, 1160 psi).

 - ○
Detection Time 3 seconds or more 3 seconds or more
Number of Trips 1 trip 1 trip

Tech Tips

DTC will be output when conditions for either of the patterns in the table above are met.

WIRING DIAGRAM

Refer to DTC C1249.

Click here

CAUTION / NOTICE / HINT

Note


  • When replacing the skid control ECU (brake actuator assembly), perform system variant learning and acceleration sensor zero point calibration.

    Click here

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

PROCEDURE


  1. READ VALUE USING GTS (BS1 VOLTAGE VALUE)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.


      Chassis > ABS/VSC/TRC > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      BS1 Voltage Value +BS voltage value Min.: 0.00 V, Max.: 20.00 V - Changes in proportion to battery voltage

      Chassis > ABS/VSC/TRC > Data List
      Tester Display
      BS1 Voltage Value

    4. Take a note of the +BS voltage value.

      Tech Tips

      The noted +BS voltage value is used in a later step.

      Result
      Proceed to
      NEXT

    NEXT

  2. CHECK BRAKE PEDAL AND STOP LIGHT SWITCH ASSEMBLY INSTALLATION


    1. Check the brake pedal height installation.

      for LHD: Click here

      for RHD: Click here

    2. Check the stop light switch assembly installation.

      Click here

      OK
      The brake pedal height and stop light switch assembly installation are normal.

      Tech Tips

      If the on/off status of the stop light switch assembly and pressure increase information from the master cylinder pressure sensor do not match due to an improperly installed brake pedal or stop light switch assembly, this DTC may be stored. Therefore, be sure to check the installation condition of the pedal and switch before inspecting the input signals and other related parts.

      Result
      Proceed to
      OK
      NG

    NG

    ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH ASSEMBLY for LHD: Click here
    ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH ASSEMBLY for RHD: Click here

    OK

  3. 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
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT STOP LIGHT SWITCH ASSEMBLY Click here

    OK

  4. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. Inspect the stop light switch assembly.

      Click here

      OK
      The stop light switch assembly is normal.
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

  5. READ VALUE USING GTS (STOP LIGHT SWITCH ASSEMBLY)


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.


      Chassis > ABS/VSC/TRC > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Stop Light SW Stop light switch assembly ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

      		 -

      Chassis > ABS/VSC/TRC > Data List
      Tester Display
      Stop Light SW

    4. Check that the stop light switch assembly display observed on the GTS changes according to brake pedal operation.

      OK
      The GTS displays on or off according to brake pedal operation.
      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (STP TERMINAL) Click here

    OK

  6. RECONFIRM DTC


    1. Clear the DTCs.


      Chassis > ABS/VSC/TRC > Clear DTCs

    2. Turn the ignition switch off.

    3. Start the engine.

    4. Drive the vehicle at a speed of 3 km/h (2 mph) or more and depress the brake pedal several times to test the stop light circuit.

    5. Check if the same DTC is output.


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      C1426 is not output A
      C1426 is output B

    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here

  7. CHECK HARNESS AND CONNECTOR (STP TERMINAL)


    1. B0071RIC71
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

      Turn the ignition switch off.

    2. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK
      The connector is securely connected.

    3. Disconnect the A34 skid control ECU (brake actuator assembly) connector.

    4. Check both the connector case and the terminals for deformation and corrosion.

      OK
      No deformation or corrosion.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A34-42 (STP) - Body ground Stop light switch assembly on (Brake pedal depressed) (+BS x 0.85) to 14 V*

      Tech Tips

      *: The minimum voltage value varies depending on the +BS terminal voltage value. The minimum voltage is 85% or more of the +BS terminal voltage.

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

    OK

  8. CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)


    1. B0071RIC70
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A34-46 (GND1) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

  9. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. Inspect the stop light switch assembly.

      Click here

      OK
      The stop light switch assembly is normal.
      Result
      Proceed to
      OK
      NG

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

  10. CHECK HARNESS AND CONNECTOR (STP TERMINAL)


    1. B0071RIC71
      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

      Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK
      The connector is securely connected.

    2. Disconnect the A34 skid control ECU (brake actuator assembly) connector.

    3. Check both the connector case and the terminals for deformation and corrosion.

      OK
      No deformation or corrosion.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A34-42 (STP) - Body ground Stop light switch assembly on (Brake pedal depressed) (+BS x 0.85) to 14 V*
      A34-42 (STP) - Body ground Stop light switch assembly off (Brake pedal released) Below 1.5 V

      Tech Tips

      *: The minimum voltage value varies depending on the +BS terminal voltage value. The minimum voltage is 85% or more of the +BS terminal voltage.

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

    OK

  11. RECONFIRM DTC


    1. Reconnect the A34 skid control ECU (brake actuator assembly) connector.

    2. Clear the DTCs.


      Chassis > ABS/VSC/TRC > Clear DTCs

    3. Turn the ignition switch off.

    4. Start the engine.

    5. Drive the vehicle at a speed of 3 km/h (2 mph) or more and depress the brake pedal several times to test the stop light circuit.

    6. Check if the same DTC is output.


      Chassis > ABS/VSC/TRC > Trouble Codes
      Result
      Result Proceed to
      C1426 is not output A
      C1426 is output B

      Tech Tips

      If the lighting system is normal but the DTC is still output, replace the skid control ECU (brake actuator assembly).

      for LHD: Click here

      for RHD: Click here


    A

    USE SIMULATION METHOD TO CHECK Click here

    B

    INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT) Click here