VEHICLE STABILITY CONTROL SYSTEM, Diagnostic DTC:C1426

DTC Code DTC Name
C1426 Stop Light Switch OFF Stuck Malfunction

DESCRIPTION

The skid control ECU (housed in the actuator assembly) inputs stop light switch signals and the condition of brake operation.

The skid control ECU has an open detection circuit, which outputs this DTC when detecting an open in the stop light input line or the ground line of the stop light circuit with the stop light switch off (brake pedal not depressed).

DTC Code DTC Detection Condition Trouble Area
C1426 When the brake pedal load sensing switch is ON, the master cylinder pressure is 2 MPa or more and the deceleration calculated from the vehicle speed is 0.2 G or more, the stop light switch is OFF for 2 seconds or more.

  • STOP fuse

  • Stop light switch

  • Stop light switch circuit

  • Stop light control relay

  • Stop light control relay circuit

  • Brake actuator assembly (Skid control ECU)

WIRING DIAGRAM

Refer to DTC C1425 Click here.

INSPECTION PROCEDURE

Note

When replacing the brake actuator assembly, perform zero point calibration Click here.

PROCEDURE


  1. 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

    NG

    INSPECT STOP FUSE Click here

    OK

  2. READ VALUE ON INTELLIGENT TESTER (STOP LIGHT SWITCH)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch on (IG).

    3. Select the Data List mode on the intelligent tester Click here.

      ABS / VSC / TRC:
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light SW Stop light switch / ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

      		 -
      Brake Pedal Load Sensing SW Brake pedal load sensing switch / ON or OFF

      ON: Brake pedal depressed beyond the specified point

      OFF: Brake pedal not depressed beyond the specified point

      		 -

    4. Check that the stop light switch display and brake pedal load sensing switch display observed on the intelligent tester change according to brake pedal operation.

      OK
      The intelligent tester displays ON or OFF according to brake pedal operation.

    5. Slowly depress the brake pedal, and check when the stop light switch and brake pedal load sensing switch turn ON.

      OK
      First the stop light switch should turn ON, and then the brake pedal load sensing switch should turn ON.
      Result
      Result Proceed to
      OK A
      NG (Turning on of the stop light switch is not confirmed) B
      NG (The brake pedal load sensing switch turns on first) C

    B

    CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - ENGINE ROOM RELAY BLOCK) Click here

    C

    CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION Click here

    A

  3. RECONFIRM DTC


    1. Turn the ignition switch off.

    2. Clear the DTCs Click here.

    3. Start the engine.

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

    5. Check if the same DTC is recorded Click here.

      Result
      Result Proceed to
      DTC (C1426) is not output A
      DTC (C1426) is output B

      Tech Tips

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


    B

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    A

    CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION) Click here

  4. INSPECT STOP FUSE


    1. A017FBOE02

      Remove the STOP fuse from the main body ECU (instrument panel junction block).

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

      Standard resistance
      Tester Connection Condition Specified Condition
      STOP (10 A) fuse Always Below 1 Ω

    NG

    REPLACE STOP FUSE

    OK

  5. INSPECT STOP LIGHT SWITCH (POWER SOURCE TERMINAL)


    1. A017GBJE13

      Install the STOP fuse.

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

    3. Disconnect the stop light switch connector.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      A20-2 - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

    OK

  6. INSPECT STOP LIGHT SWITCH


    1. A017BK7E03

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

      Standard resistance
      Tester Connection Switch Condition Specified Condition
      1 - 2 Switch pin free Below 1 Ω
      1 - 2 Switch pin pushed in 10 kΩ or higher

    NG

    REPLACE STOP LIGHT SWITCH Click here

    OK

  7. INSPECT STOP LIGHT CONTROL RELAY


    1. A017B3RE06

      Remove the stop light control relay.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      3 - 4 Voltage is not applied between terminals 1 and 2 Below 1 Ω

    NG

    REPLACE STOP LIGHT CONTROL RELAY

    OK

  8. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ENGINE ROOM RELAY BLOCK)


    1. A017B4KE02

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

      Standard resistance
      Tester Connection Condition Specified Condition
      A20-1 - Stop light control relay terminal 4 Always Below 1 Ω
      A20-1 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  9. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - ENGINE ROOM RELAY BLOCK)


    1. A017E2EE01

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

    2. Disconnect the skid control ECU connector.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      A24-2 (STP) - Stop light control relay terminal 3 Always Below 1 Ω
      A24-2 (STP) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. RECONFIRM DTC


    1. Clear the DTCs Click here.

    2. Start the engine.

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

    4. Check if the same DTC is recorded Click here.

      Tech Tips

      Reinstall the relay, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.

      Result
      Result Proceed to
      DTC (C1426) is not output A
      DTC (C1426) is output B

      Tech Tips

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


    B

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    A

    INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT) Click here

  11. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - ENGINE ROOM RELAY BLOCK)


    1. A017E2EE01

      Turn the ignition switch off.

    2. Remove the stop light control relay.

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

    4. Disconnect the skid control ECU connector.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      A24-2 (STP) - Stop light control relay terminal 3 Always Below 1 Ω
      A24-2 (STP) - Body ground Always 10 kΩ or higher

      Tech Tips

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


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

  12. CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION


    1. Turn the ignition switch off.

    2. Check the brake pedal height and stop light switch installation Click here.

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

      Tech Tips

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


    NG

    ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH Click here

    OK

    REPLACE BRAKE PEDAL SUB-ASSEMBLY (BRAKE PEDAL LOAD SENSING SWITCH) Click here