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 line or the ground line of the stop light circuit with the stop light switch assembly 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.

DTC Detection Condition

Trouble Area

C1426

Either of the following is detected:

  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 (STP circuit)

  • Wire harness or connector (GND1 circuit)

  • Stop light switch assembly

  • Skid control ECU (brake actuator assembly)

WIRING DIAGRAM

Refer to DTC C1380 (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. CHECK BRAKE PEDAL AND STOP LIGHT SWITCH ASSEMBLY INSTALLATION

    1. Check the brake pedal height installation (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.

      Tip:

      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.

    ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH ASSEMBLY

    (Click here)

  2. CHECK STOP LIGHT OPERATION

    Click here

    INSPECT STOP LIGHT SWITCH ASSEMBLYClick here

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

    Click here

    CHECK TERMINAL VOLTAGE (STP TERMINAL)Click here

  4. RECONFIRM DTC

    1. Turn the ignition switch off.

    2. Clear the DTCs (Click here).

    3. Turn the ignition switch off.

    4. Start the engine.

    5. Depress the brake pedal several times to test the stop light circuit.

    6. Check if the same DTC is output (Click here).

      Result

      Result

      Proceed to

      DTC C1426 is not output.

      A

      DTC C1426 is output.

      B
      Tip:

      If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step (Click here).

    USE SIMULATION METHOD TO CHECK

    (Click here)

    REPLACE BRAKE ACTUATOR ASSEMBLY

    (Click here)

  5. CHECK TERMINAL VOLTAGE (STP TERMINAL)

    1. U123608E01

      Turn the ignition switch off.

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

    3. Disconnect the A78 (for CVT) or A79 (except CVT) skid control ECU (brake actuator assembly) connector.

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

      Standard Voltage (for CVT)

      Tester Connection

      Condition

      Specified Condition

      A78-30 (STP) - Body ground

      Stop light switch assembly ON (Brake pedal depressed)

      11 to 14 V*

      Standard Voltage (except CVT)

      Tester Connection

      Condition

      Specified Condition

      A79-6 (STP) - Body ground

      Stop light switch assembly ON (Brake pedal depressed)

      11 to 14 V*
      Table 1. Text in Illustration

      *A

      for CVT

      *B

      except CVT

      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))
      Tip:

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

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

  6. CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)

    1. U123607E01

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

      Standard Resistance (for CVT)

      Tester Connection

      Condition

      Specified Condition

      A78-38 (GND1) - Body ground

      Always

      Below 1 Ω

      Standard Resistance (except CVT)

      Tester Connection

      Condition

      Specified Condition

      A79-14 (GND1) - Body ground

      Always

      Below 1 Ω
      Table 2. Text in Illustration

      *A

      for CVT

      *B

      except CVT

      *a

      Front view of wire harness connector

      (to Skid Control ECU (Brake Actuator Assembly))

    REPLACE BRAKE ACTUATOR ASSEMBLY

    (Click here)

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

  7. INSPECT STOP LIGHT SWITCH ASSEMBLY

    Click here

    REPLACE STOP LIGHT SWITCH ASSEMBLY

    (Click here)

  8. CHECK TERMINAL VOLTAGE (STP AND STP2 TERMINAL)

    Click here

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STP OR STP2 CIRCUIT)

  9. RECONFIRM DTC

    1. Reconnect the A78 (for CVT) or A79 (except CVT) skid control ECU (brake actuator assembly) connector.

    2. Clear the DTCs (Click here).

    3. Turn the ignition switch off.

    4. Start the engine.

    5. Depress the brake pedal several times to test the stop light circuit.

    6. Check if the same DTC is output (Click here).

      Result

      Result

      Proceed to

      DTC C1426 is not output.

      A

      DTC C1426 is output.

      B
      Tip:

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

    USE SIMULATION METHOD TO CHECK

    (Click here)

    INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT)

    (Click here)