BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: C1426; Stop Light Switch OFF Stuck Malfunction; 2018 - 2020 MY Sienna [11/2017

Last Modified: 04-05-2023	6.11:8.1.0	Doc ID: RM1000000018KEQ
Model Year Start: 2018	Model: Sienna	Prod Date Range: [11/2017 - ]
Title: BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: C1426; Stop Light Switch OFF Stuck Malfunction; 2018 - 2020 MY Sienna [11/2017 - ]

DTC

C1426

Stop Light Switch OFF Stuck Malfunction

DESCRIPTION

The skid control ECU (brake actuator assembly) inputs stop light switch signals and the condition of brake operation.

The skid control ECU (brake actuator assembly) 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 No.	DTC Detection Condition	Trouble Area
C1426	When the brake pedal load sensing switch is on, the master cylinder pressure is 2 MPa (20.4 kgf/cm², 290 psi) or more and the deceleration calculated from the vehicle speed is 0.2 G or more, the stop light switch assembly is off for 2 seconds or more.	Wire harness or connector Stop light switch assembly Brake pedal load sensing switch (brake pedal support assembly) Skid control ECU (brake actuator assembly)

WIRING DIAGRAM

Refer to DTCs C1425 (See page ).

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 inspection procedure.

PROCEDURE

1.	CHECK BRAKE PEDAL HEIGHT AND STOP LIGHT SWITCH ASSEMBLY INSTALLATION

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

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 the 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 stop light switch assembly before inspecting the input signals and other related parts.

ADJUST BRAKE PEDAL HEIGHT OR STOP LIGHT SWITCH ASSEMBLY INSTALLATION

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

GO TO STEP 5

3.	READ VALUE USING TECHSTREAM (STOP LIGHT SWITCH ASSEMBLY AND BRAKE PEDAL LOAD SENSING SWITCH)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Select the Data List using the Techstream (See page ).

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

Brake Pedal Load Sensing SW

Brake pedal load sensing switch / ON or OFF

ON: Brake pedal depressed beyond a specified point

OFF: Brake pedal not depressed beyond a specified point

(e) Check that the stop light switch assembly display and brake pedal load sensing switch display observed on the Techstream change according to brake pedal operation.

OK:

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

(f) Slowly depress the brake pedal, and check when the stop light switch assembly and brake pedal load sensing switch turn on.

OK:

First the stop light switch assembly should turn on, and then the brake pedal load sensing switch should turn on.

Result	Proceed to
OK	A
NG (The stop light switch assembly does not turn on.)	B
NG (Turning on of the brake pedal load sensing switch is not confirmed.)	C
NG (The brake pedal load sensing switch turns on first.)	D

GO TO STEP 10

GO TO STEP 12

REPLACE BRAKE PEDAL LOAD SENSING SWITCH (BRAKE PEDAL SUPPORT ASSEMBLY)

4.	RECONFIRM DTC

(a) Turn the ignition switch off.

(b) Clear the DTCs (See page ).

(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 (See page ).

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) for Bulb Type Stop Light

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

Standard Resistance:

Tester Connection	Switch Condition	Specified Condition
1 - 2	Switch pin released	Below 1 Ω
1 - 2	Switch pin pushed in	10 kΩ or higher

Text in Illustration

*a	Component without harness connected (Stop Light Switch Assembly)

(b) for LED Type Stop Light

(1) Reconnect the stop light switch assembly connector.

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

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
A59-2 (L) - A59-3 (GND)	Switch pin released	8 to 14 V
A59-2 (L) - A59-3 (GND)	Switch pin pushed in	Below 1.5 V

Text in Illustration

*a	Component with harness connected (Stop Light Switch Assembly)

Result

Result	Proceed to
OK (w/ Toyota Safety Sense P)	A
OK (w/o Toyota Safety Sense P)	B
NG	C

GO TO STEP 8

REPLACE STOP LIGHT SWITCH ASSEMBLY

6.	CHECK HARNESS AND CONNECTOR (SWITCH INPUT TERMINAL)

(a) Turn the ignition switch off.

(b) Remove the STOP LP relay.

Standard Voltage:

Tester Connection	Switch Condition	Specified Condition
STOP LP relay terminal 4 - Body ground	Stop light switch assembly ON (Brake pedal depressed)	8 to 14 V
STOP LP relay terminal 4 - Body ground	Stop light switch assembly OFF (Brake pedal released)	Below 1.5 V

Text in Illustration

*1	Engine Room Relay Block
*2	STOP LP Relay Holder

REPAIR OR REPLACE HARNESS OR CONNECTOR (SWITCH INPUT CIRCUIT)

7.	INSPECT STOP LP RELAY

(a) 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
3 - 4	Voltage is applied between terminals 1 and 2	10 kΩ or higher

Text in Illustration

*1	STOP LP Relay

REPLACE STOP LP RELAY

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 connectors.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
A75-35 (STP) - Body ground	Stop light switch assembly on (Brake pedal depressed)	8 to 14 V
A75-35 (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))

HINT:

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

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

9.	RECONFIRM DTC

(a) Turn the ignition switch off.

(b) Reconnect the A75 skid control ECU (brake actuator assembly) connector.

(d) Turn the ignition switch off.

(e) Start the engine.

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

(g) Check if the same DTC is output (See page ).

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

INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT)

10.	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
A75-35 (STP) - Body ground	Stop light switch assembly ON (Brake pedal depressed)	8 to 14 V
A75-35 (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))

HINT:

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

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP CIRCUIT)

11.	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
A75-25 (GND1) - Body ground	Always	Below 1 Ω

Text in Illustration

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

HINT:

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

REPLACE BRAKE ACTUATOR ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

12.	INSPECT BRAKE PEDAL LOAD SENSING SWITCH (BRAKE PEDAL SUPPORT ASSEMBLY)

(a) Turn the ignition switch off.

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

NOTICE:

Do not remove the brake pedal load sensing switch from the brake pedal support assembly.
When there is a malfunction in the brake pedal load sensing switch, replace the brake pedal support assembly.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2 - 1

Brake pedal load sensing switch off

(Brake pedal depressed)

950 to 1050 Ω

2 - 1

Brake pedal load sensing switch on

(Brake pedal released)

203 to 223 Ω

Text in Illustration

*a	Component without harness connected (Brake Pedal Load Sensing Switch (Brake Pedal Support Assembly))

REPLACE BRAKE PEDAL LOAD SENSING SWITCH (BRAKE PEDAL SUPPORT ASSEMBLY)

13.	CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - BRAKE PEDAL SUPPORT ASSEMBLY)

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

(b) Disconnect the A75 skid control ECU (brake actuator assembly) connectors.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A75-23 (FSW+) - A7-2	Always	Below 1 Ω
A75-23 (FSW+) - Body ground	Always	10 kΩ or higher
A7-1 - Body ground	Always	Below 1 Ω

HINT:

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

REPLACE BRAKE ACTUATOR ASSEMBLY

REPAIR OR REPLACE HARNESS OR CONNECTOR