PRE-CRASH SAFETY SYSTEM, Diagnostic DTC:C1A4B

DTC Code DTC Name
C1A4B Stop Light Relay Circuit

DESCRIPTION

The brake actuator assembly (skid control ECU) sends a stop light operation signal to the stop light switch assembly. When the brake actuator assembly (skid control ECU) detects a malfunction in the stop light circuit, the driving support ECU assembly stores DTC C1A4B.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

C1A4B

Stop Light Relay Circuit

Either of the following conditions is met:

  • When the ignition switch ON, the IG1 terminal voltage is between 11 to 14 V and the stop light illumination output signal (STPO) is output, the signal is not received at terminal STP for 0.3 seconds or more.

  • When the ignition switch ON, the IG1 terminal voltage is between 11 to 14 V and the stop light illumination output signal (STPO) is not output, the signals received at terminals STP and STP2 are different for 0.3 seconds or more.

  • Lighting system

  • Vehicle stability control system

  • Harness or connector

  • Stop light switch assembly

  • Brake actuator assembly (skid control ECU)

  • Entry and start system (w/ entry and start system)

WIRING DIAGRAM

E337398E02

CAUTION / NOTICE / HINT

Note:

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

  • When replacing the brake actuator assembly (skid control ECU), perform zero point calibration.

    Click here

  • When the entry and start function does not operate, check the entry and start system (start function)*.

    Click here

  • *: w/ Entry and Start System

PROCEDURE

  1. CHECK STOP LIGHT OPERATION

    1. 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

    Result

    Result

    Proceed to

    OK (w/ Entry and Start System)

    A

    OK (w/o Entry and Start System)

    B

    NG

    C
    B

    CHECK HARNESS AND CONNECTOR (STP2 TERMINAL VOLTAGE)Click here

    C

    GO TO LIGHTING SYSTEM

    Click here

    A

  2. CHECK HARNESS AND CONNECTOR (STPO TERMINAL VOLTAGE)

    1. Turn the ignition switch off.

    2. E296982C19

      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly [Skid Control ECU])

      Disconnect the brake actuator assembly (skid control ECU) connector.

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A80-26 (STPO) - Body ground

      Always

      11 to 14 V

    Result

    Proceed to

    OK

    NG
    NG

    CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BRAKE ACTUATOR ASSEMBLY [SKID CONTROL ECU])Click here

    OK

  3. PERFORM ACTIVE TEST USING GTS (STOP LIGHT RELAY)

    1. Enter the following menus: Chassis / ABS/VSC/TRC / Active Test.

    2. Perform "Active Test" according to the display on GTS.

      Chassis > ABS/VSC/TRC > Active Test

      Tester Display

      Measurement Item

      Control Range

      Diagnostic Note

      Stop Light Relay

      Stop lights

      ON or OFF

      Test possible at vehicle speed of 0 km/h (0 mph)

      Chassis > ABS/VSC/TRC > Active Test

      Tester Display

      Stop Light Relay

    3. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.

    4. Check the stop light switch assembly operation using the Data List and stop light operation by performing an Active Test.

      Chassis > ABS/VSC/TRC > Data List

      Tester Display

      Measurement Item

      Range

      Normal Condition

      Diagnostic Note

      Stop Light Relay Output

      Stop light control relay output

      ON or OFF

      ON: Relay output on (Stop light on)

      OFF: Relay output off (Stop light off)

      -

      Chassis > ABS/VSC/TRC > Data List

      Tester Display

      Stop Light Relay

    Result

    Result

    Proceed to

    When Active Test performed, Data List item not changes between ON and OFF

    A

    When Active Test performed, Data List item changes between ON and OFF and stop lights turn on and off

    B
    B

    CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BRAKE ACTUATOR ASSEMBLY [SKID CONTROL ECU])Click here

    A

  4. INSPECT BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU)

    1. Enter the following menus: Chassis / ABS/VSC/TRC / Active Test.

    2. Perform "Active Test" according to the display on GTS.

      Chassis > ABS/VSC/TRC > Active Test

      Tester Display

      Measurement Item

      Control Range

      Diagnostic Note

      Stop Light Relay

      Stop lights

      ON or OFF

      Test possible at vehicle speed of 0 km/h (0 mph)

      Chassis > ABS/VSC/TRC > Active Test

      Tester Display

      Stop Light Relay
    3. E337400C01

      *a

      Component with harness connected

      (Stop Light Switch Assembly)

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A77-4 (ACC) - Body ground

      Active test is OFF

      11 to 14 V

      A77-4 (ACC) - Body ground

      Active test is ON

      Below 1.5 V

    Result

    Proceed to

    OK

    NG
    OK

    REPLACE STOP LIGHT SWITCH ASSEMBLY

    Click here

    NG

    REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU)

    Click here

  5. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BRAKE ACTUATOR ASSEMBLY [SKID CONTROL ECU])

    1. Disconnect the A80 brake actuator assembly (skid control ECU) connector.

    2. Disconnect the A77 stop light switch assembly connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      A80-35 (STP) - A77-1 (OUT)

      Always

      Below 1 Ω

    Result

    Proceed to

    OK

    NG
    OK

    REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU)

    Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  6. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BRAKE ACTUATOR ASSEMBLY [SKID CONTROL ECU])

    1. Disconnect the A80 brake actuator assembly (skid control ECU) connector.

    2. Disconnect the A77 stop light switch assembly connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      A80-26 (STPO) - A77-4 (ACC)

      Always

      Below 1 Ω

      A80-26 (STPO) or A77-4 (ACC) - Body ground

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    OK

    REPLACE STOP LIGHT SWITCH ASSEMBLY

    Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  7. CHECK HARNESS AND CONNECTOR (STP2 TERMINAL VOLTAGE)

    1. Turn the ignition switch off.

    2. E296982C20

      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly [Skid Control ECU])

      Disconnect the brake actuator assembly (skid control ECU) connector.

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

      Standard Voltage

      Tester Connection

      Switch Condition

      Specified Condition

      A80-5 (STP2) - Body ground

      Stop light switch assembly on (Brake pedal depressed)

      8.5 to 14 V

      A80-5 (STP2) - Body ground

      Stop light switch assembly off (Brake pedal released)

      Below 1.5 V

    Result

    Proceed to

    OK

    NG
    OK

    CHECK HARNESS AND CONNECTOR (STPO TERMINAL VOLTAGE)Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR