Toyota Tundra Service Manual: Stop Light Switch OFF Stuck Malfunction (C1426)

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

With the stop light switch assembly off, the master cylinder pressure is more than 1.5 MPa (15.3 kgf/cm2, 217 psi) for 1 second or more.

  • Wire harness or connector
  • Stop light switch assembly
  • Skid Control ECU (brake Actuator Assembly)

WIRING DIAGRAM

Refer to DTC C1249.

Click here

CAUTION / NOTICE / HINT

NOTICE:

  • 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

(a) Check the brake pedal height installation.

Click here

(b) Check the stop light switch assembly installation.

Click here

OK:

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

HINT:

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.

NG

ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH ASSEMBLY

OK

2.

CHECK STOP LIGHT OPERATION

(a) 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

GO TO STEP 8

OK

3.

INSPECT STOP LIGHT SWITCH ASSEMBLY

(a) Check the stop light switch assembly.

Click here

OK:

The stop light switch assembly is normal.

NG

REPLACE STOP LIGHT SWITCH ASSEMBLY

OK

4.

READ VALUE USING TECHSTREAM (STOP LIGHT SWITCH ASSEMBLY)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.

ABS/VSC/TRAC

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

-

(d) Check that the stop light switch assembly display observed on the Techstream changes according to brake pedal operation.

OK:

The Techstream displays on or off according to brake pedal operation.

NG

GO TO STEP 6

OK

5.

RECONFIRM DTC

(a) Clear the DTCs.

Click here

(b) Turn the ignition switch off.

(c) Start the engine.

(d) Depress the brake pedal several times to test the stop light circuit.

(e) Check if the same DTC is output.

Click here

Result

Proceed to

C1426 is not output

A

C1426 is output

B

A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE ACTUATOR ASSEMBLY

6.

CHECK HARNESS AND CONNECTOR (STP TERMINAL)

(a) Turn the ignition switch off.

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

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

OK:

The connector is securely connected.

(c) Disconnect the A57 skid control ECU (brake actuator assembly) connector.

(d) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A57-2 (STP) - Body ground

Stop light switch assembly on (Brake pedal depressed)

8 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

OK

7.

CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A57-38 (GND1) - Body ground

Always

Below 1 Ω

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

OK

REPLACE BRAKE ACTUATOR ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

8.

INSPECT STOP LIGHT SWITCH ASSEMBLY

(a) Check the stop light switch assembly.

Click here

OK:

The stop light switch assembly is normal.

NG

REPLACE STOP LIGHT SWITCH ASSEMBLY

OK

9.

CHECK HARNESS AND CONNECTOR (STP TERMINAL)

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

OK:

The connector is securely connected.

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

(b) Disconnect the A57 skid control ECU (brake actuator assembly) connector.

(c) Check both the connector case and the terminals for deformation and corrosion.

OK:

No deformation or corrosion.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A57-2 (STP) - Body ground

Stop light switch assembly on (Brake pedal depressed)

8 to 14 V

A57-2 (STP) - Body ground

Stop light switch assembly off (Brake pedal released)

Below 1.5 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

OK

10.

RECONFIRM DTC

(a) Reconnect the A57 skid control ECU (brake actuator assembly) connector.

(b) Clear the DTCs.

Click here

(c) Turn the ignition switch off.

(d) Start the engine.

(e) Depress the brake pedal several times to test the stop light circuit.

(f) Check if the same DTC is output.

Click here

Result

Proceed to

C1426 is not output

A

C1426 is output

B

HINT:

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

Click here

A

USE SIMULATION METHOD TO CHECK

B

INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT)

    Open in Stop Light Switch Circuit (C1425)

    Motor Circuit Malfunction (C1428)

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