PRE-CRASH SAFETY SYSTEM, Diagnostic DTC:C1A4B

DTC Code DTC Name
C1A4B Stop Light Relay Circuit

DESCRIPTION

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

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

Both of the following conditions are met:


  1. All of the following conditions are met:


    • 3 seconds have elapsed since the power switch was turned to ON.

    • The auxiliary battery voltage is 10 V or more for 3 seconds or more.

  2. All of the following conditions are met for 1 second or more:


    • Communication between the driving support ECU assembly and skid control ECU (brake booster with master cylinder assembly) is normal.

    • The driving support ECU assembly receives a stop light relay circuit malfunction signal from the skid control ECU (brake booster with master cylinder assembly)

Tech Tips

The skid control ECU (brake booster with master cylinder assembly) will detect a stop light relay circuit malfunction if any of the following conditions are met:


  • When the voltage at the IG1 terminal is between 11 V and 14 V and the stop light illumination output (STPO) signal is on, a signal has not been input to the STP terminal continuously for 0.3 seconds or more.

  • When the voltage at the IG1 terminal is between 11 V and 14 V and the stop light illumination output (STPO) signal is off, the input signals at the STP terminal and STP2 terminal differ continuously for 0.3 seconds or more.


  • Skid control ECU (Brake booster with master cylinder assembly)

  • Stop light relay (Stop light switch assembly)

  • Rear combination light assembly LH

  • Rear combination light assembly RH

  • Center stop light set

  • hybrid vehicle control ECU

  • certification ECU (smart key ECU assembly)

  • Harness or connector

WIRING DIAGRAM

A003KY2E06

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


  1. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) CONNECTOR)


    1. Turn the power switch off.

    2. A003P2IC09
      *a

      Front view of wire harness connector

      (to Skid control ECU (Brake booster with master cylinder assembly))

      Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-37 (STP2) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V
      A32-22 (STPO) - Body ground Power switch ON 11 to 14 V
      A32-12 (STP) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V
    4. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Result Proceed to
      The voltage is as specified for every terminal. A
      Only the voltage at terminal STP2 is not as specified. B
      Only the voltage at terminal STPO is not as specified. C
      Only the voltage at terminal STP is not as specified. D
      The voltage at both terminal STPO and terminal STP are not as specified. E

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


    1. Turn the power switch off.

    2. According to the display on the GTS, perform the Active Test Stop Light Relay.

      Click here


      Chassis > ABS/VSC/TRC > Active Test
      Tester Display Measurement Item Control Range Diagnostic Note
      Stop Light Relay Stop light relay (Stop light switch assembly) ON / OFF Test possible at vehicle speed of 0 km/h (0 mph)

      Chassis > ABS/VSC/TRC > Active Test
      Tester Display
      Stop Light Relay
      OK
      The stop lights turn on and off correctly in response to the operation of the Active Test.
      Result
      Proceed to
      OK
      NG

    NG
    OK
  3. CHECK FOR DTCS (PRE-CRASH SAFETY SYSTEM)


    1. Clear the DTCs.

      Click here


      Body Electrical > Pre-Crash 2 > Clear DTCs
    2. According to the display on the GTS, perform the Active Test Stop Light Relay.

      Click here


      Chassis > ABS/VSC/TRC > Active Test
      Tester Display Measurement Item Control Range Diagnostic Note
      Stop Light Relay Stop light relay (Stop light switch assembly) ON / OFF Test possible at vehicle speed of 0 km/h (0 mph)

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

      Click here


      Body Electrical > Pre-Crash 2 > Trouble Codes
      OK
      DTC C1A4B is not output
      Result
      Proceed to
      OK
      NG

    OK
    NG
  4. INSPECT SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY)


    1. According to the display on the GTS, perform the Active Test Stop Light Relay.

      Click here


      Chassis > ABS/VSC/TRC > Active Test
      Tester Display Measurement Item Control Range Diagnostic Note
      Stop Light Relay Stop light relay (Stop light switch assembly) ON / OFF Test possible at vehicle speed of 0 km/h (0 mph)

      Chassis > ABS/VSC/TRC > Active Test
      Tester Display
      Stop Light Relay
    2. A003OMVC51
      *a

      Component with harness connected

      (Stop light relay (stop light switch assembly))

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

      Tech Tips

      Do not disconnect the stop light relay (stop light switch assembly) connector.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A38-4 (ACC) - Body ground

      Power switch on (IG)

      (Active test ON)

      Below 1.5 V
      Result
      Proceed to
      OK
      NG

    OK
    NG
  5. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) CONNECTOR)


    1. Turn the power switch off.

    2. A003P2IC10
      *a

      Front view of wire harness connector

      (to Skid control ECU (Brake booster with master cylinder assembly))

      Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-37 (STP2) - Body ground Brake pedal released Below 1.5 V
    4. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    NG
    OK
  6. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the N54 certification ECU (smart key ECU assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-37 (STP2) or N54-25 (STP1) - Body ground Brake pedal depressed 11 to 14 V
    5. Connect the N54 certification ECU (smart key ECU assembly) connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  7. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - HYBRID VEHICLE CONTROL ECU)


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the A41 hybrid vehicle control ECU connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-37 (STP2) or A41-7 (STP) - Body ground Brake pedal depressed 11 to 14 V
    5. Connect the A41 hybrid vehicle control ECU connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  8. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - STOP LIGHT RELAY (STOP LIGHT SWITCH ASSEMBLY))


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the A38 stop light relay (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
      A32-37 (STP2) - A38-3 (L) Always Below 1 Ω
      A32-37 (STP2) or A38-3 (L) - Body ground Always 10 kΩ or higher
    5. Connect the A38 stop light relay (stop light switch assembly) connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  9. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - STOP LIGHT RELAY (STOP LIGHT SWITCH ASSEMBLY))


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the A38 stop light relay (stop light switch assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-37 (STP2) or A38-3 (L) - Body ground Brake pedal released Below 1.5 V
    5. Connect the A38 stop light relay (stop light switch assembly) connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  10. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the N54 certification ECU (smart key ECU assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-37 (STP2) or N54-25 (STP1) - Body ground Brake pedal released Below 1.5 V
    5. Connect the N54 certification ECU (smart key ECU assembly) connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  11. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - HYBRID VEHICLE CONTROL ECU)


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the A41 hybrid vehicle control ECU connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-37 (STP2) or A41-7 (STP) - Body ground Brake pedal released Below 1.5 V
    5. Connect the A41 hybrid vehicle control ECU connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  12. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - STOP LIGHT RELAY (STOP LIGHT SWITCH ASSEMBLY))


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the A38 stop light relay (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
      A32-22 (STPO) - A38-4 (ACC) Always Below 1 Ω
    5. Connect the A38 stop light relay (stop light switch assembly) connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    NG
    OK
  13. INSPECT STOP LIGHT RELAY (STOP LIGHT SWITCH ASSEMBLY) (POWER SOURCE CIRCUIT)


    1. Turn the power switch off.

    2. A003KHVC99
      *a

      Front view of wire harness connector

      (to Stop light relay (Stop light switch assembly))

      Disconnect the A38 stop light relay (stop light switch assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A38-6 (B) - Body ground Power switch ON 11 to 14 V
      A38-7 (B) - Body ground Always 11 to 14 V
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A38-2 (GND) - Body ground Always Below 1 Ω
    5. Connect the A38 stop light relay (stop light switch assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  14. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) CONNECTOR)


    1. Turn the power switch off.

    2. A003P2IC11
      *a

      Front view of wire harness connector

      (to Skid control ECU (Brake booster with master cylinder assembly))

      Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-12 (STP) - Body ground Brake pedal released Below 1.5 V
    4. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    NG
    OK
  15. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - REAR COMBINATION LIGHT ASSEMBLY LH)


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the N37 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
      A32-12 (STP) or N37-3 (STP) - Body ground Brake pedal depressed 11 to 14 V
    5. Connect the N37 rear combination light assembly LH connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  16. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - REAR COMBINATION LIGHT ASSEMBLY RH)


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the N36 rear combination light assembly RH connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-12 (STP) or N36-3 (STP) - Body ground Brake pedal depressed 11 to 14 V
    5. Connect the N36 rear combination light assembly RH connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  17. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - CENTER STOP LIGHT SET)


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the R7 center stop light set connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-12 (STP) or R7-1 (B) - Body ground Brake pedal depressed 11 to 14 V
    5. Connect the R7 center stop light set connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  18. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - STOP LIGHT RELAY (STOP LIGHT SWITCH ASSEMBLY))


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the A38 stop light relay (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
      A32-12 (STP) - A38-1 (OUT) Always Below 1 Ω
      A32-12 (STP) or A38-1 (OUT) - Body ground Always 10 kΩ or higher
    5. Connect the A38 stop light relay (stop light switch assembly) connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  19. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - STOP LIGHT RELAY (STOP LIGHT SWITCH ASSEMBLY))


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the A38 stop light relay (stop light switch assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-12 (STP) or A38-1 (OUT) - Body ground Brake pedal released Below 1.5 V
    5. Connect the A38 stop light relay (stop light switch assembly) connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  20. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - REAR COMBINATION LIGHT ASSEMBLY LH)


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the N37 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
      A32-12 (STP) or N37-3 (STP) - Body ground Brake pedal released Below 1.5 V
    5. Connect the N37 rear combination light assembly LH connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  21. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - REAR COMBINATION LIGHT ASSEMBLY RH)


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the N36 rear combination light assembly RH connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-12 (STP) or N36-3 (STP) - Body ground Brake pedal released Below 1.5 V
    5. Connect the N36 rear combination light assembly RH connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  22. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - CENTER STOP LIGHT SET)


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the R7 center stop light set connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-12 (STP) or R7-1 (B) - Body ground Brake pedal released Below 1.5 V
    5. Connect the R7 center stop light set connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  23. INSPECT STOP LIGHT RELAY (STOP LIGHT SWITCH ASSEMBLY) (POWER SOURCE CIRCUIT)


    1. Turn the power switch off.

    2. A003KHVC99
      *a

      Front view of wire harness connector

      (to Stop light relay (Stop light switch assembly))

      Disconnect the A38 stop light relay (stop light switch assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A38-6 (B) - Body ground Power switch ON 11 to 14 V
      A38-7 (B) - Body ground Always 11 to 14 V
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A38-2 (GND) - Body ground Always Below 1 Ω
    5. Connect the A38 stop light relay (stop light switch assembly) connector.

      Result
      Proceed to
      OK
      NG

    NG
    OK
  24. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - STOP LIGHT RELAY (STOP LIGHT SWITCH ASSEMBLY))


    1. Turn the power switch off.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

    3. Disconnect the A38 stop light relay (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
      A32-22 (STPO) or A38-4 (ACC) - Body ground Always 10 kΩ or higher
    5. Connect the A38 stop light relay (stop light switch assembly) connector.

    6. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

      Result
      Proceed to
      OK
      NG

    OK
    NG