PRE-CRASH SAFETY SYSTEM, Diagnostic DTC:C1A4B

DTC Code DTC Name
C1A4B Stop Light Relay Circuit

DESCRIPTION

The master cylinder solenoid (skid control ECU) sends a stop light operation request signal to the stop light control relay assembly. If the master cylinder solenoid (skid control ECU) detects a malfunction in the stop light relay circuit, the driving support ECU assembly stores DTC C1A4B.

Vehicle Condition
Pattern 1 Pattern 2
Diagnosis Condition IG1 terminal voltage is 11 to 14 V ○ ○
Stop Light illumination output (STPO) ON ○ -
Stop Light illumination output (STPO) OFF - ○
Malfunction Status No signal input to STP2 terminal ○ -
Signals input to STP and STP2 terminals do not match - ○
Malfunction Time 0.3 seconds or more 0.3 seconds or more
Number of Trips - -
DTC No. DTC Detection Condition Trouble Area
C1A4B

Either of the following conditions is met:


  • When the engine switch is on (IG), the IG1 terminal voltage is between 11 and 14 V and the stop light illumination output signal (STPO) is output, the signal is not received at terminal STP2 for 0.3 seconds or more.

  • When the stop light illumination output (STPO) signal is off, signals input to the STP terminal and STP2 terminal of the master cylinder solenoid (skid control ECU) differ for 0.3 seconds or more continuously.

  • Lighting system

  • Stop light control relay assembly

  • Master cylinder solenoid (Skid control ECU)

  • Harness or connector

WIRING DIAGRAM

B001AKWE03

CAUTION / NOTICE / HINT

Note


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

  • After replacing the master cylinder solenoid, perform zero point calibration and store the system information Click here.

  • When the start function does not operate, check the Entry and Start System (for start function) Click here.

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

    NG

    GO TO LIGHTING SYSTEM Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (STPO TERMINAL VOLTAGE)


    1. Turn the engine switch off.

    2. B0018TZE01
      Text in Illustration
      *a Front view of wire harness connector (to Master Cylinder Solenoid [Skid Control ECU])

      Disconnect the master cylinder solenoid (skid control ECU) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A24-16 (STPO) - Body ground Engine switch on (IG) 11 to 14 V

    NG

    CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY - MASTER CYLINDER SOLENOID [SKID CONTROL ECU]) Click here

    OK

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


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

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

      ABS/VSC/TRAC
      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Stop lights ON / OFF Test possible at vehicle speed of 0 km/h (0 mph)

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

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

      ABS/VSC/TRAC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light Relay Output STOP terminal output condition/ON or OFF

      ON: Output

      OFF: Not output

      		 -
      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 (STP2 TERMINAL VOLTAGE) Click here

    A

  4. INSPECT MASTER CYLINDER SOLENOID (SKID CONTROL ECU)


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

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

      ABS/VSC/TRAC
      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Stop lights ON / OFF Test possible at vehicle speed of 0 km/h (0 mph)
    3. B0019SIE01
      Text in Illustration
      *a

      Component with harness connected

      (Stop Light Control Relay Assembly)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A58-9 (ACC) - Body ground Active test is ON Below 1.5 V
      Result
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

    B

    REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) Click here

    C

    REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) Click here

    A

  5. REPLACE STOP LIGHT CONTROL RELAY ASSEMBLY


    1. Replace the stop light control relay assembly.

      for LHD: Click here

      for RHD: Click here


    NEXT

  6. CHECK FOR DTC


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

      Tech Tips

      If the detection conditions are not met, the system cannot detect the malfunction.


      • Using the GTS, perform the Active Test "Stop Light Relay" with the ignition switch to ON.

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

      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Stop lights ON / OFF Test possible at vehicle speed of 0 km/h (0 mph)
      EBS Relay

      Stop light control relay

      (Emergency brake signal)

      		 ON / OFF -

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

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

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light Relay Output STOP terminal output condition/ON or OFF

      ON: Output

      ON: Not output

      		 -
      EBS Relay Stop light control relay (Emergency brake signal)/ON or OFF

      ON: Relay on

      OFF: Relay off

      		 -

    5. Clear the DTCs Click here.

    6. Check for DTCs Click here.

      Result
      Result Proceed to
      DTC C1380 is output A
      DTC C1380 is not output B

    A

    GO TO DTC C1380 Click here

    B

    END (STOP LIGHT CONTROL RELAY ASSEMBLY WAS DEFECTIVE)

  7. CHECK HARNESS AND CONNECTOR (STP2 TERMINAL VOLTAGE)


    1. Turn the engine switch off.

    2. B0018MEE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Master Cylinder Solenoid [Skid Control ECU])

      Disconnect the master cylinder solenoid (skid control ECU) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A24-45 (STP2) - Body ground Brake pedal depressed 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU)


    1. Replace the master cylinder solenoid (skid control ECU).

      for LHD: Click here

      for RHD: Click here


    NEXT

  9. CHECK FOR DTC


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

      Tech Tips

      If the detection conditions are not met, the system cannot detect the malfunction.


      • Using the GTS, perform the Active Test "Stop Light Relay" with the ignition switch to ON.

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

      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Stop lights ON / OFF Test possible at vehicle speed of 0 km/h (0 mph)
      EBS Relay

      Stop light control relay

      (Emergency brake signal)

      		 ON / OFF -

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

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

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light Relay Output STOP terminal output condition/ON or OFF

      ON: Output

      ON: Not output

      		 -
      EBS Relay Stop light control relay (Emergency brake signal)/ON or OFF

      ON: Relay on

      OFF: Relay off

      		 -

    5. Clear the DTCs Click here.

    6. Check for DTCs Click here.

      Result
      Result Proceed to
      DTC C1380 is output A
      DTC C1380 is not output B

    A

    GO TO DTC C1380 Click here

    B

    END (STOP LIGHT CONTROL RELAY ASSEMBLY WAS DEFECTIVE)

  10. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY ASSEMBLY - MASTER CYLINDER SOLENOID [SKID CONTROL ECU])


    1. Disconnect the A58 stop light control relay assembly connector.

    2. Disconnect the A24 master cylinder solenoid (skid control ECU) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A58-9 (ACC) - A24-16 (STPO) Always Below 1 Ω
      A58-9 (ACC) or A24-16 (STPO) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  11. REPLACE STOP LIGHT CONTROL RELAY ASSEMBLY


    1. Replace the stop light control relay assembly.

      for LHD: Click here

      for RHD: Click here


    NEXT

  12. CHECK FOR DTC


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

      Tech Tips

      If the detection conditions are not met, the system cannot detect the malfunction.


      • Using the GTS, perform the Active Test "Stop Light Relay" with the ignition switch to ON.

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

      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Stop lights ON / OFF Test possible at vehicle speed of 0 km/h (0 mph)
      EBS Relay

      Stop light control relay

      (Emergency brake signal)

      		 ON / OFF -

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

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

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light Relay Output STOP terminal output condition/ON or OFF

      ON: Output

      ON: Not output

      		 -
      EBS Relay Stop light control relay (Emergency brake signal)/ON or OFF

      ON: Relay on

      OFF: Relay off

      		 -

    5. Clear the DTCs Click here.

    6. Check for DTCs Click here.

      Result
      Result Proceed to
      DTC C1380 is output A
      DTC C1380 is not output B

    A

    GO TO DTC C1380 Click here

    B

    END (STOP LIGHT CONTROL RELAY ASSEMBLY WAS DEFECTIVE)