Toyota Tundra Service Manual: Open in Stop Light Switch Circuit (C1425)

Toyota Tundra Service Manual / Brake / Brake Control / Dynamic Control Systems / Vehicle Stability Control System / Open in Stop Light Switch Circuit (C1425)

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 an open in the stop light input line.

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

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

C1425

Open in Stop Light Switch Circuit

With the stop light control relay not operating, an open circuit continuously occurs in the input line of the stop light switch assembly for 2.5 seconds or more.
  • Wire harness or connector
  • Stop light switch assembly
  • Skid control ECU (brake actuator assembly)

WIRING DIAGRAM

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 STOP LIGHT SWITCH OPERATION

(a) Check that all 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 LIGHT CIRCUIT

OK

2.

CHECK HARNESS AND CONNECTOR (STP TERMINAL)

(a) Turn the ignition switch off.

(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

A57-2 (STP) - Body ground

Stop light switch assembly off (Brake pedal released)

Below 1.5 V

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)
OK

3.

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

C1425 is not output

A

C1425 is output

B
A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE ACTUATOR ASSEMBLY

    Acceleration Sensor Malfunction (C1420)

    Stop Light Switch OFF Stuck Malfunction (C1426)

    See More:

    Toyota Tundra Service Manual > Propeller Shaft Assembly(for 2wd): Installation
    INSTALLATION PROCEDURE 1. MEASURE EXTENSION HOUSING AND DIFFERENTIAL FLANGE ANGLE NOTICE: Perform the inspection on a level surface. Perform the inspection with the vehicle empty. Perform the inspection with all wheels on the ground. HINT: As the extension housing and rear differential flange angles ...

    Toyota Tundra Owners Manual

    Toyota Tundra Service Manual

    © 2026 Copyright www.ttundra.com
    0.0137