Toyota Tacoma (2015-2018) Service Manual: Stop Light Switch OFF Stuck Malfunction (C1426)

Toyota Tacoma (2015-2018) Service Manual / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Vacuum Brake Booster) / Stop Light Switch OFF Stuck Malfunction (C1426)

DESCRIPTION

The skid control ECU (brake actuator assembly) inputs the stop light signal and brake operation condition. When the brake pedal is depressed and the stop light switch signal is not input, C1426 is output.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
C1426	Stop Light Switch OFF Stuck Malfunction	When voltage at terminal +BS is 9.5 V or higher, vehicle is driven and brake pedal is operated, stop light switch signal is not input.	Wire harness or connector STOP fuse Stop light switch assembly Skid Control ECU (Brake actuator assembly)

WIRING DIAGRAM

Refer to DTC C1380 (See page CAUTION / NOTICE / HINT ).

CAUTION / NOTICE / HINT

NOTICE:

When replacing the skid control ECU (brake actuator assembly), perform zero point calibration and store system information (See page ).
Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.	CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION

(a) Check the brake pedal height installation (See page (b) Check the stop light switch assembly installation (See page ).

(b) Check the stop light switch assembly installation (See page OK: ).

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.

ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH ASSEMBLY

2.	CHECK STOP LIGHT 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

GO TO STEP 5

3.	READ VALUE USING TECHSTREAM (STOP LIGHT SWITCH ASSEMBLY)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

ABS/VSC/TRAC

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	-

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

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

OK:

The Techstream displays ON or OFF according to brake pedal operation.

GO TO STEP 8

4.	RECONFIRM DTC

(a) Turn the ignition switch off.

(b) Clear the DTCs (See page (c) Start the engine. ).

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

(e) Check if the same DTC is recorded (See page Result Result ).

Result

Result	Proceed to
DTC C1426 is not output.	A
DTC C1426 is output.	B

HINT:

If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step (See page ).

USE SIMULATION METHOD TO CHECK

REPLACE BRAKE ACTUATOR ASSEMBLY

5.	INSPECT STOP LIGHT SWITCH ASSEMBLY

(a) Check the stop light switch assembly (See page OK: ).

OK:

The stop light switch assembly is normal.

REPLACE STOP LIGHT SWITCH ASSEMBLY

6.	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.

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
S1-35 (STP) - Body ground	Stop light switch assembly on (Brake pedal depressed)	8 to 14 V
S1-35 (STP) - Body ground	Stop light switch assembly off (Brake pedal released)	Below 1.5 V

Text in Illustration

*a	Front view of wire harness connector (to Skid Control ECU (Brake Actuator Assembly))

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

7.	RECONFIRM DTC

(a) Reconnect the S1 skid control ECU (brake actuator assembly) connector.

(b) Clear the DTCs (See page (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 recorded (See page Result Result ).

Result

Result	Proceed to
DTC C1426 is not output.	A
DTC C1426 is output.	B

USE SIMULATION METHOD TO CHECK

INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT)

8.	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.

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
S1-35 (STP) - Body ground	Stop light switch assembly on (Brake pedal depressed)	8 to 14 V
S1-35 (STP) - Body ground	Stop light switch assembly off (Brake pedal released)	Below 1.5 V

Text in Illustration

*a	Front view of wire harness connector (to Skid Control ECU (Brake Actuator Assembly))

REPLACE BRAKE ACTUATOR ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

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