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.

WIRING DIAGRAM

Refer to DTC C1249.

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CAUTION / NOTICE / HINT

NOTICE:

• When replacing the skid control ECU (brake actuator assembly), perform system variant learning and acceleration sensor zero point calibration.

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• Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

(a) Check the brake pedal height installation.

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(b) Check the stop light switch assembly installation.

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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

(a) Check that the stop lights come on when the brake pedal is depressed, and go off when the brake pedal is released.

OK:

NG

GO TO STEP 8

OK

(a) Check the stop light switch assembly.

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OK:

The stop light switch assembly is normal.

NG

REPLACE STOP LIGHT SWITCH ASSEMBLY

OK

(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.

(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

(a) Clear the DTCs.

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(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.

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A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE ACTUATOR ASSEMBLY

(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:

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

OK

(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)

(a) Check the stop light switch assembly.

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OK:

The stop light switch assembly is normal.

NG

REPLACE STOP LIGHT SWITCH ASSEMBLY

OK

(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:

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

OK

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

(b) Clear the DTCs.

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(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.

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HINT:

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

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A

USE SIMULATION METHOD TO CHECK

B

INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT)