Toyota Tundra Service Manual: Stop Light Control Relay Malfunction (C1380)

DESCRIPTION

When the skid control ECU (brake actuator assembly) applies the brakes after receiving a brake request signal from the trailer sway control, the skid control ECU (brake actuator assembly) operates the stop light switch assembly to illuminate the stop lights.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

C1380

Stop Light Control Relay Malfunction

Either condition is met:

  • When the voltage at the +BS terminal is between 10 V or more and the light switch assembly drive output (STPO) is on, a signal is not input to the STP2 terminal for 2 seconds or more.
  • When the voltage at the +BS terminal is between 10 V or more and the stop light switch assembly drive output (STPO) is off, the signal at the STP2 terminal is different from the input signal at the STP terminal for 5 seconds or more.
  • Wire harness or connector
  • Stop light switch assembly
  • Skid control ECU (brake actuator assembly)
  • ECU-IG1 NO. 2 fuse
  • Stop light control relay (VSC ACC)

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.

HINT:

When DTC C1425 is output together with DTC C1380, inspect and repair the trouble areas indicated by DTC C1425 first.

Click here

PROCEDURE

1.

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

INSPECT STOP LIGHT CIRCUIT

OK

2.

CHECK HARNESS AND CONNECTOR (STP2 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

A57-12 (STP2) - Body ground

Stop light switch assembly on (Brake pedal depressed)

8 to 14 V

A57-12 (STP2) - Body ground

Stop light switch assembly off (Brake pedal released)

Below 1.5 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (STP2 CIRCUIT)

OK

3.

CHECK HARNESS AND CONNECTOR (STPO TERMINAL)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A57-28 (STPO) - Body ground

Ignition switch ON

11 to 14 V

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

NG

GO TO STEP 8

OK

4.

PERFORM ACTIVE TEST USING TECHSTREAM (STOP LIGHT RELAY)

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

(b) Connect the Techstream to the DLC3.

(c) Start the engine.

(d) Turn the Techstream on.

(e) Enter the following menus: Chassis / ABS/VSC/TRAC / Active Test.

ABS/VSC/TRAC

Tester Display

Measurement Item

Control Range

Diagnostic Note

Stop Light Relay

Stop light Control Relay (VSC ACC)

Relay OFF/ON

Stop lights come on

OK:

Stop light turns ON/OFF in response to the Techstream operation

NG

GO TO STEP 6

OK

5.

CHECK FOR DTC

(a) Clear the DTCs.

Click here

(b) Enter the following menus: Chassis / ABS/VSC/TRAC / Active Test.

ABS/VSC/TRAC

Tester Display

Measurement Item

Control Range

Diagnostic Note

Stop Light Relay

Stop light control relay (VSC ACC)

Relay OFF/ON

Stop lights come on

(c) According to the display on the Techstream, perform the Active Test.

(d) Check if the same DTC is output.

Click here

Result

Proceed to

C1380 is output

A

C1380 is not output

B

A

REPLACE BRAKE ACTUATOR ASSEMBLY

B

USE SIMULATION METHOD TO CHECK

6.

INSPECT STOP LIGHT CONTROL RELAY (VSC ACC)

(a) Turn the ignition switch off.

(b) Remove the stop light control relay (VSC ACC) from the engine room relay block and junction block assembly

(c) Inspect the stop light control relay (VSC ACC).

Click here

OK:

The stop light control relay (VSC ACC) is normal.

NG

REPLACE STOP LIGHT CONTROL RELAY (VSC ACC)

OK

7.

CHECK TERMINAL VOLTAGE (STOP LIGHT POWER SOURCE TERMINAL)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

Stop light control relay (VSC ACC) terminal 5- Body ground

Always

11 to 14 V

*1

Engine Room Relay Block and Junction Block Assembly

*2

Stop Light Control Relay (VSC ACC)

*a

Component without Stop Light Control Relay (VSC ACC)

(Engine Room Relay Block and Junction Block Assembly)

OK

REPLACE BRAKE ACTUATOR ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

8.

INSPECT STOP LIGHT CONTROL RELAY (VSC ACC)

(a) Turn the ignition switch off.

(b) Remove the stop light control relay (VSC ACC) from the engine room relay block and junction block assembly

(c) Inspect the stop light control relay (VSC ACC).

Click here

OK:

The stop light control relay (VSC ACC) is normal.

NG

REPLACE STOP LIGHT CONTROL RELAY (VSC ACC)

OK

9.

CHECK TERMINAL VOLTAGE (STOP LIGHT CONTROL RELAY POWER SOURCE TERMINAL)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

Stop light control relay (VSC ACC) terminal 1 - Body ground

Ignition switch ON

11 to 14 V

*1

Engine Room Relay Block and Junction Block Assembly

*2

Stop Light Control Relay (VSC ACC)

*a

Component without Stop Light Control Relay (VSC ACC)

(Engine Room Relay Block and Junction Block Assembly)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

10.

CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - ENGINE ROOM RELAY BLOCK AND JUNCTION BLOCK ASSEMBLY)

(a) Turn the ignition switch off.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A57-28 (STPO) - Stop light control relay (VSC ACC) terminal 2

Always

Below 1 Ω

OK

REPLACE BRAKE ACTUATOR ASSEMBLY

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

    Center Differential Lock Circuit (C1340)

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