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 relay (STP LP OPE). 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 relay (STP LP OPE)

  • Master cylinder solenoid (Skid control ECU)

  • Harness or connector

WIRING DIAGRAM

B001WS6E14

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
      The stop lights illuminate when the brake pedal is depressed. The stop lights turn off when the brake pedal is released.

    NG

    GO TO LIGHTING SYSTEM Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (MASTER CYLINDER SOLENOID [SKID CONTROL ECU] STPO TERMINAL VOLTAGE)


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

    2. B001XJWE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Master Cylinder Solenoid [Skid Control ECU])

      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 RELAY [STP LP OPE] - MASTER CYLINDER SOLENOID [SKID CONTLOR ECU] AND BATTERY) Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (MASTER CYLINDER SOLENOID [SKID CONTROL ECU] STP2 TERMINAL VOLTAGE)


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

    2. B001XNRE06
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Master Cylinder Solenoid [Skid Control ECU])

      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

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


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

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

      ABS/VSC/TRAC
      Tester Display Test Part Control Range Diagnostic Note
      Stop Light Relay Stop light relay (STP LP OPE) Relay ON/OFF Observe the stop light (the stop lights do not come on for 2 to 5 seconds).

    3. Check the stop light relay (STP LP OPE) 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 light relay (STP LP OPE) output/ ON or OFF

      ON: Relay output on (Stop light on)

      OFF: Relay output off (Stop light off)

      		 -
      Result
      Result Proceed to
      The Data List item "Stop Light Relay Output" switches between ON and OFF when turning the stop light control relay on and off with the Active Test, but the stop lights do not illuminate or turn off A
      The Data List item "Stop Light Relay Output" does not switch between ON and OFF when turning the stop light control relay on and off with the Active Test (for LHD) B
      The Data List item "Stop Light Relay Output" switches between ON and OFF when turning the stop light control relay on and off with the Active Test and the stop lights illuminate and turn off (for LHD)
      The Data List item "Stop Light Relay Output" does not switch between ON and OFF when turning the stop light control relay on and off with the Active Test (for RHD) C
      The Data List item "Stop Light Relay Output" switches between ON and OFF when turning the stop light control relay on and off with the Active Test and the stop lights illuminate and turn off (for RHD)

    B

    REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) Click here

    C

    REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) Click here

    A

  5. INSPECT STOP LIGHT RELAY (STP LP OPE)


    1. Turn the engine switch off.

    2. Remove the stop light relay (STP LP OPE) from the engine room relay block and junction block assembly.

    3. Inspect the stop light relay (STP LP OPE) Click here.


    NG

    REPLACE STOP LIGHT RELAY (STP LP OPE)

    OK

  6. CHECK HARNESS AND CONNECTOR (STOP LIGHT RELAY [STP LP OPE] - BATTERY)


    1. Turn the engine switch off.

    2. Remove the stop light relay (STP LP OPE) from the engine room relay block and junction block assembly.

    3. B001ZIDE08
      Text in Illustration
      *1 Engine Room Relay Block and Junction Block Assembly
      *2 Stop Light Relay (STP LP OPE) Holder Terminal

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      Stop light relay (STP LP OPE) holder terminal 5 - Body ground Always 11 to 14 V
      OK
      Result Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG C

    A

    REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) Click here

    B

    REPLACE MASTER CYLINDER SOLENOID (SKID CONTROL ECU) Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  7. CHECK HARNESS AND CONNECTOR (STOP LIGHT RELAY [STP LP OPE] - MASTER CYLINDER SOLENOID [SKID CONTLOR ECU] AND BATTERY)


    1. Turn the engine switch off.

    2. Remove the stop light relay (STP LP OPE) from the engine room relay block and junction block assembly.

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

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      Stop light relay (STP LP OPE) holder terminal 2 - A24-16 (STPO) Always Below 1 Ω
      Stop light relay (STP LP OPE) holder terminal 2 or A24-16 (STPO) - Body ground Always 10 kΩ or higher
    5. B001ZIDE09
      Text in Illustration
      *1 Engine Room Relay Block and Junction Block Assembly
      *2 Stop Light Relay (STP LP OPE) Holder Terminal

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      Stop light relay (STP LP OPE) holder terminal 1 - Body ground Engine switch on (IG) 11 to 14 V

    OK

    REPLACE STOP LIGHT RELAY (STP LP OPE)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR