PRE-COLLISION SYSTEM, Diagnostic DTC:C1A4B

DTC Code DTC Name
C1A4B Stop Light Relay Circuit

DESCRIPTION

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

DTC No. Detection Item DTC Detection Condition Trouble Area
C1A4B Stop Light Relay Circuit

Diagnosis condition:


  • Engine switch is on (IG) and battery voltage between 8.9 V or more

Malfunction condition:

Either of the following conditions is met:


  • When the stop light illumination output (STPO) signal is on, a signal has not been input to the STP2 terminal for 0.3 seconds or more continuously.

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


  • Skid control ECU (brake actuator assembly)

  • Stop light switch assembly

  • Stop light control ECU assembly

  • Rear combination light assembly LH

  • Rear combination light assembly RH

  • Rear light assembly LH

  • Rear light assembly RH

  • Center stop light assembly

  • ECM

  • Shift lock control unit assembly

  • Certification ECU (smart key ECU assembly)

  • Harness or connector

WIRING DIAGRAM

B00584LE01
B005AQME01
B0057D4E01

CAUTION / NOTICE / HINT

Note


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

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

    Click here

  • Before replacing the certification ECU (smart key ECU assembly), refer to Service Bulletin.

PROCEDURE


  1. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) CONNECTOR)


    1. Turn the engine switch off.

    2. B005883C75
      *a

      Front view of harness connector

      (to Skid control ECU (brake actuator assembly))

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

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-35 (STP) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V
      A36-26 (STPO) - Body ground Engine switch on (IG) 11 to 14 V
      A36-5 (STP2) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V
    4. Connect the skid control ECU (brake actuator assembly) connector.

      Result
      Result Proceed to
      All terminal voltage is normal A
      Only STP terminal voltage abnormal B
      Only STPO terminal voltage abnormal C
      Only STP2 terminal voltage abnormal D
      STPO terminal and STP2 terminal voltage abnormal E

    B
    C
    D
    E
    A
  2. PERFORM ACTIVE TEST USING GTS (STOP LIGHT RELAY)


    1. Turn the engine switch off.

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

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

      Click here


      Chassis > ABS/VSC/TRC > Active Test
      Tester Display Measurement Item Control Range Diagnostic Note
      Stop Light Relay Stop light control ECU assembly ON or OFF Stop lights come on

      Chassis > ABS/VSC/TRC > Active Test
      Tester Display
      Stop Light Relay
      OK
      Stop light turns ON/OFF in response to the GTS operation
      Result
      Proceed to
      OK
      NG

    NG
    OK
  3. CHECK FOR DTC


    1. Clear the DTCs.

      Click here


      Body Electrical > Pre-Collision 2 > Clear DTCs
    2. Enter the following menus: Chassis / ABS/VSC/TRC / Active Test.

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

      Click here


      Chassis > ABS/VSC/TRC > Active Test
      Tester Display Measurement Item Control Range Diagnostic Note
      Stop Light Relay Stop light control ECU assembly ON or OFF Stop lights come on

      Chassis > ABS/VSC/TRC > Active Test
      Tester Display
      Stop Light Relay
    4. Check for DTCs.

      Click here


      Body Electrical > Pre-Collision 2 > Trouble Codes
      Result
      Result Proceed to
      DTC C1A4B is output. A
      DTC C1A4B is not output. B

    A
    B
  4. INSPECT SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY)


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

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


      Chassis > ABS/VSC/TRC > Active Test
      Tester Display Measurement Item Control Range Diagnostic Note
      Stop Light Relay Stop light control ECU assembly ON or OFF Stop lights come on

      Chassis > ABS/VSC/TRC > Active Test
      Tester Display
      Stop Light Relay
    3. B00589XC33
      *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
      A3-9 (ACC) - Body ground Active Test is ON Below 1.5 V
      Result
      Proceed to
      OK
      NG

    OK
    NG
  5. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - ECM)


    1. Turn the engine switch off.

    2. B005883C76
      *a

      Front view of harness connector

      (to Skid control ECU (brake actuator assembly))

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

    3. Disconnect the A35 ECM connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-35 (STP) - Body ground Brake pedal depressed 8 to 14 V
      A36-35 (STP) - Body ground Brake pedal released Below 1.5 V
    5. Connect the A35 ECM connector.

    6. Connect the skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  6. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - SHIFT LOCK CONTROL UNIT ASSEMBLY)


    1. Turn the engine switch off.

    2. B005883C76
      *a

      Front view of harness connector

      (to Skid control ECU (brake actuator assembly))

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

    3. Disconnect the A35 ECM connector.

    4. Disconnect the I22 shift lock control unit assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-35 (STP) - Body ground Brake pedal depressed 8 to 14 V
      A36-35 (STP) - Body ground Brake pedal released Below 1.5 V
    6. Connect the I22 shift lock control unit assembly connector.

    7. Connect the A35 ECM connector.

    8. Connect the skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  7. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))


    1. Turn the engine switch off.

    2. B005883C76
      *a

      Front view of harness connector

      (to Skid control ECU (brake actuator assembly))

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

    3. Disconnect the A35 ECM connector.

    4. Disconnect the I22 shift lock control unit assembly connector.

    5. Disconnect the I51 certification ECU (smart key ECU assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-35 (STP) - Body ground Brake pedal depressed 8 to 14 V
      A36-35 (STP) - Body ground Brake pedal released Below 1.5 V
    7. Connect the I51 certification ECU (smart key ECU assembly) connector.

    8. Connect the I22 shift lock control unit assembly connector.

    9. Connect the A35 ECM connector.

    10. Connect the skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  8. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - STOP LIGHT CONTROL ECU ASSEMBLY)


    1. Turn the engine switch off.

    2. B005883C76
      *a

      Front view of harness connector

      (to Skid control ECU (brake actuator assembly))

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

    3. Disconnect the A35 ECM connector.

    4. Disconnect the I22 shift lock control unit assembly connector.

    5. Disconnect the I51 certification ECU (smart key ECU assembly) connector.

    6. Disconnect the A3 stop light control ECU assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-35 (STP) - Body ground Brake pedal depressed 8 to 14 V
      A36-35 (STP) - Body ground Brake pedal released Below 1.5 V
    8. Connect the A3 stop light control ECU assembly connector.

    9. Connect the I51 certification ECU (smart key ECU assembly) connector.

    10. Connect the I22 shift lock control unit assembly connector.

    11. Connect the A35 ECM connector.

    12. Connect the skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  9. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - STOP LIGHT SWITCH ASSEMBLY)


    1. Turn the engine switch off.

    2. B005883C76
      *a

      Front view of harness connector

      (to Skid control ECU (brake actuator assembly))

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

    3. Disconnect the A35 ECM connector.

    4. Disconnect the I22 shift lock control unit assembly connector.

    5. Disconnect the I51 certification ECU (smart key ECU assembly) connector.

    6. Disconnect the A3 stop light control ECU assembly connector.

    7. Disconnect the A1 stop light switch assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-35 (STP) - Body ground Always Below 1.5 V
    9. Connect the A1 stop light switch assembly connector.

    10. Connect the A3 stop light control ECU assembly connector.

    11. Connect the I51 certification ECU (smart key ECU assembly) connector.

    12. Connect the I22 shift lock control unit assembly connector.

    13. Connect the A35 ECM connector.

    14. Connect the skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    NG
    OK
  10. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - STOP LIGHT SWITCH ASSEMBLY)


    1. Turn the engine switch off.

    2. Disconnect the A36 skid control ECU (brake actuator assembly) connector.

    3. Disconnect the A1 stop light switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A36-35 (STP) - A1-2 (L) Always Below 1 Ω
      A36-35 (STP) or A1-2 (L) - Body ground Always 10 kΩ or higher
    5. Connect the A1 stop light switch assembly connector.

    6. Connect the A36 skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  11. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - STOP LIGHT CONTROL ECU ASSEMBLY)


    1. Turn the engine switch off.

    2. Disconnect the A36 skid control ECU (brake actuator assembly) connector.

    3. Disconnect the A3 stop light control ECU assemblyconnector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A36-26 (STPO) - A3-9 (ACC) Always Below 1 Ω
    5. Connect the A3 stop light control ECU assemblyconnector.

    6. Connect the A36 skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  12. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - REAR COMBINATION LIGHT ASSEMBLY LH)


    1. Turn the engine switch off.

    2. B005883C77
      *a

      Front view of harness connector

      (to Skid control ECU (brake actuator assembly))

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

    3. Disconnect the Q16 rear combination light assembly LH connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-5 (STP2) - Body ground Brake pedal depressed 8 to 14 V
      A36-5 (STP2) - Body ground Brake pedal released Below 1.5 V
    5. Connect the Q16 rear combination light assembly LH connector.

    6. Connect the skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  13. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - REAR COMBINATION LIGHT ASSEMBLY RH)


    1. Turn the engine switch off.

    2. B005883C77
      *a

      Front view of harness connector

      (to Skid control ECU (brake actuator assembly))

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

    3. Disconnect the Q16 rear combination light assembly LH connector.

    4. Disconnect the P13 rear combination light assembly RH connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-5 (STP2) - Body ground Brake pedal depressed 8 to 14 V
      A36-5 (STP2) - Body ground Brake pedal released Below 1.5 V
    6. Connect the P13 rear combination light assembly RH connector.

    7. Connect the Q16 rear combination light assembly LH connector.

    8. Connect the skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  14. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - REAR LIGHT ASSEMBLY LH)


    1. Turn the engine switch off.

    2. B005883C77
      *a

      Front view of harness connector

      (to Skid control ECU (brake actuator assembly))

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

    3. Disconnect the Q16 rear combination light assembly LH connector.

    4. Disconnect the P13 rear combination light assembly RH connector.

    5. Disconnect the Y11 rear light assembly LH connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-5 (STP2) - Body ground Brake pedal depressed 8 to 14 V
      A36-5 (STP2) - Body ground Brake pedal released Below 1.5 V
    7. Connect the Y11 rear light assembly LH connector.

    8. Connect the P13 rear combination light assembly RH connector.

    9. Connect the Q16 rear combination light assembly LH connector.

    10. Connect the skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  15. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - REAR LIGHT ASSEMBLY RH)


    1. Turn the engine switch off.

    2. B005883C77
      *a

      Front view of harness connector

      (to Skid control ECU (brake actuator assembly))

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

    3. Disconnect the Q16 rear combination light assembly LH connector.

    4. Disconnect the P13 rear combination light assembly RH connector.

    5. Disconnect the Y11 rear light assembly LH connector.

    6. Disconnect the Y10 rear light assembly RH connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-5 (STP2) - Body ground Brake pedal depressed 8 to 14 V
      A36-5 (STP2) - Body ground Brake pedal released Below 1.5 V
    8. Connect the Y10 rear light assembly RH connector.

    9. Connect the Y11 rear light assembly LH connector.

    10. Connect the P13 rear combination light assembly RH connector.

    11. Connect the Q16 rear combination light assembly LH connector.

    12. Connect the skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  16. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - CENTER STOP LIGHT ASSEMBLY)


    1. Turn the engine switch off.

    2. B005883C77
      *a

      Front view of harness connector

      (to Skid control ECU (brake actuator assembly))

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

    3. Disconnect the Q16 rear combination light assembly LH connector.

    4. Disconnect the P13 rear combination light assembly RH connector.

    5. Disconnect the Y11 rear light assembly LH connector.

    6. Disconnect the Y10 rear light assembly RH connector.

    7. Disconnect the e1 center stop light assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-5 (STP2) - Body ground Brake pedal depressed 8 to 14 V
      A36-5 (STP2) - Body ground Brake pedal released Below 1.5 V
    9. Connect the e1 center stop light assembly connector.

    10. Connect the Y10 rear light assembly RH connector.

    11. Connect the Y11 rear light assembly LH connector.

    12. Connect the P13 rear combination light assembly RH connector.

    13. Connect the Q16 rear combination light assembly LH connector.

    14. Connect the skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  17. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - STOP LIGHT CONTROL ECU ASSEMBLY)


    1. Turn the engine switch off.

    2. B005883C77
      *a

      Front view of harness connector

      (to Skid control ECU (brake actuator assembly))

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

    3. Disconnect the Q16 rear combination light assembly LH connector.

    4. Disconnect the P13 rear combination light assembly RH connector.

    5. Disconnect the Y11 rear light assembly LH connector.

    6. Disconnect the Y10 rear light assembly RH connector.

    7. Disconnect the e1 center stop light assembly connector.

    8. Disconnect the A3 stop light control ECU assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A36-5 (STP2) - Body ground Always Below 1.5 V
    10. Connect the A3 stop light control ECU assembly connector.

    11. Connect the e1 center stop light assembly connector.

    12. Connect the Y10 rear light assembly RH connector.

    13. Connect the Y11 rear light assembly LH connector.

    14. Connect the P13 rear combination light assembly RH connector.

    15. Connect the Q16 rear combination light assembly LH connector.

    16. Connect the skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    NG
    OK
  18. CHECK HARNESS AND CONNECTOR (+B/GND TERMINAL)


    1. B00588HC02
      *a

      Front view of harness connector

      (to Stop light control ECU assembly )

      Turn the engine switch off.

    2. Disconnect the A3 stop light control ECU assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A3-6 (+B) - Body ground Always 11 to 14V
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A3-8 (GND) - Body ground Always Below 1 Ω
    5. Connect the A3 stop light control ECU assembly connector.

      Result
      Proceed to
      OK
      NG

    NG
    OK
  19. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - STOP LIGHT CONTROL ECU ASSEMBLY)


    1. Turn the engine switch off.

    2. Disconnect the A36 skid control ECU (brake actuator assembly) connector.

    3. Disconnect the A3 stop light control ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A3-1 (OUT) - A36-5 (STP2) Always Below 1 Ω
      A3-1 (OUT) or A36-5 (STP2) - Body ground Always 10 kΩ or higher
    5. Connect the A3 stop light control ECU assembly connector.

    6. Connect the A36 skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  20. CHECK HARNESS AND CONNECTOR (+B/GND TERMINAL)


    1. B00588HC03
      *a

      Front view of harness connector

      (to Stop light control ECU assembly )

      Turn the engine switch off.

    2. Disconnect the A3 stop light control ECU assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A3-6 (+B) - Body ground Always 11 to 14V
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A3-8 (GND) - Body ground Always Below 1 Ω
    5. Connect the A3 stop light control ECU assembly connector.

      Result
      Proceed to
      OK
      NG

    NG
    OK
  21. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - STOP LIGHT CONTROL ECU ASSEMBLY)


    1. Turn the engine switch off.

    2. Disconnect the A36 skid control ECU (brake actuator assembly) connector.

    3. Disconnect the A3 stop light control ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A3-1 (OUT) - A36-5 (STP2) Always Below 1 Ω
      A3-1 (OUT) or A36-5 (STP2) - Body ground Always 10 kΩ or higher
    5. Connect the A3 stop light control ECU assembly connector.

    6. Connect the A36 skid control ECU (brake actuator assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG