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 SW fuse

  • Stop light switch

  • Stop light switch circuit

  • Stop light control (BRK-LP) relay

  • Stop light control (BRK-LP) 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 and store system information 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 SW FUSE Click here

    OK

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


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Select the Data List 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 are turned on.

      OK
      First the stop light switch is turned on, and then the brake pedal load sensing switch is turned on.
      Result
      Result Proceed to
      OK A
      NG (The stop light switch is not turned on) B
      NG (The brake pedal load sensing switch is turned on first) C

    B

    CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - STOP LIGHT SWITCH) Click here

    C

    CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION Click here

    A

  3. RECONFIRM DTC


    1. Turn the engine 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 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 Click here

  4. INSPECT STOP SW FUSE


    1. A0163J7E12
      Text in Illustration
      *1 Main Body ECU RH
      *2 STOP SW Fuse

      Remove the STOP SW fuse from the main body ECU RH (cowl side junction block RH).

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      STOP SW (7.5 A) fuse Always Below 1 Ω

    NG

    REPLACE STOP SW FUSE

    OK

  5. INSPECT STOP LIGHT SWITCH (POWER SOURCE TERMINAL)


    1. A015ZQ9E23
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Stop Light Switch)

      Install the STOP SW 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
      A22-2 - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

    OK

  6. INSPECT STOP LIGHT SWITCH


    1. A0163A4E05

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

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

    NG

    REPLACE STOP LIGHT SWITCH Click here

    OK

  7. INSPECT STOP LIGHT CONTROL (BRK-LP) RELAY


    1. A015ZSVE06
      Text in Illustration
      *1 Stop Light Control (BRK-LP) Relay

      Remove the stop light control (BRK-LP) 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 (BRK-LP) RELAY

    OK

  8. INSPECT STOP LIGHT CONTROL RELAY


    1. Check the stop light control relay Click here.

      OK
      The stop light control relay is normal.

    NG

    REPLACE STOP LIGHT CONTROL RELAY Click here

    OK

  9. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - STOP LIGHT CONTROL RELAY)


    1. A015Z05E12
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Stop Light Switch)
      *2

      Front view of wire harness connector

      (to Stop Light Control Relay)

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

    2. Disconnect the stop light control relay connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A22-1 - J99-2 (STP) Always Below 1 Ω
      A22-1 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - NO. 2 ENGINE ROOM RELAY BLOCK)


    1. A0161X7E02
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Stop Light Control Relay)
      *2 No. 3 Engine Room Relay Block
      *3 Stop Light Control (BRK-LP) Relay

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      J99-8 (OUT) - Stop light control (BRK-LP) relay terminal 4 Always Below 1 Ω
      J99-8 (OUT) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  11. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - NO. 2 ENGINE ROOM RELAY BLOCK)


    1. A0161MYE01
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Skid Control ECU)
      *2 No. 3 Engine Room Relay Block
      *3 Stop Light Control (BRK-LP) Relay

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

    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
      A62-22 (STP2) - Stop light control (BRK-LP) relay terminal 3 Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  12. 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 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

  13. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - STOP LIGHT SWITCH)


    1. A0160XXE11
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Skid Control ECU)
      *2

      Front view of wire harness connector

      (to Stop Light Switch)

      Turn the engine switch off.

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

    3. Disconnect the skid control ECU connector and the stop light switch connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A62-2 (STP1) - A22-1 Always Below 1 Ω

      Tech Tips

      If troubleshooting has been carried out according to 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

  14. CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION


    1. Turn the engine 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 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 SUPPORT ASSEMBLY (BRAKE PEDAL LOAD SENSING SWITCH) Click here