PRE-COLLISION SYSTEM, Diagnostic DTC:C1A4B

DTC Code DTC Name
C1A4B Stop Light Relay Circuit

DESCRIPTION

The skid control ECU assembly sends a stop light operation request signal to the stop light relay (semiconductor power integration ECU). If the skid control ECU assembly detects a malfunction in the stop light relay (semiconductor power integration ECU) 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 (IG).

    • 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 assembly is normal.

    • The driving support ECU assembly receives a stop light relay circuit malfunction signal from the skid control ECU assembly

Tech Tips

The skid control ECU 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 STP2 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 assembly

  • Stop light relay (Semiconductor power integration ECU)

  • Rear combination light assembly LH

  • Rear combination light assembly RH

  • Center stop light assembly

  • Harness or connector

  • Vehicle Approaching Speaker Controller (w/ Vehicle Proximity Notification System)

WIRING DIAGRAM

B003YPKE01

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 ASSEMBLY CONNECTOR)


    1. Turn the power switch off.

    2. B003YQYC02
      *a

      Front view of wire harness connector

      (to Skid Control ECU Assembly)

      Disconnect the A24 and A25 skid control ECU assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A25-25 (STP) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V
      A25-31 (STPO) - Body ground Always 11 to 14 V
      A24-24 (STP2) - Body ground Brake pedal depressed 11 to 14 V
      Brake pedal released Below 1.5 V

    4. Connect the A24 and A25 skid control ECU assembly connector.

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

    B

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    C

    CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU)) Click here

    D

    INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU ASSEMBLY CONNECTOR) Click here

    E

    CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU)) Click here

    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 ON / OFF

      Stop lights come on

      Vehicle condition: Vehicle stopped

      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

    INSPECT STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU) Click here

    OK

  3. CHECK FOR DTCS (PRE-COLLISION SYSTEM)


    1. Clear the DTCs.

      Click here


      Body Electrical > Pre-Collision 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 ON / OFF

      Stop lights come on

      Vehicle condition: Vehicle stopped

      Chassis > ABS/VSC/TRC > Active Test
      Tester Display
      Stop Light Relay

    3. Check for DTCs.

      Click here


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

    OK

    USE SIMULATION METHOD TO CHECK Click here

    NG

    REPLACE SKID CONTROL ECU ASSEMBLY for LHD: Click here for RHD: Click here

  4. INSPECT STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU)


    1. Turn the power switch off.

    2. Inspect the stop light relay (semiconductor power integration ECU).

      Click here

      OK
      The stop light relay (semiconductor power integration ECU) is normal.
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE SKID CONTROL ECU ASSEMBLY for LHD: Click here for RHD: Click here

    NG

    REPLACE STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU) Click here

  5. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU))


    1. Turn the power switch off.

    2. Remove the stop light relay (semiconductor power integration ECU).

    3. Disconnect the A25 skid control ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A25-31 (STPO) - 1D-3 (ACC) Always Below 1 Ω

    5. Connect the A25 skid control ECU assembly connector.

    6. Install the stop light relay (semiconductor power integration ECU).

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU) Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  6. INSPECT TERMINAL VOLTAGE (SKID CONTROL ECU ASSEMBLY CONNECTOR)


    1. Turn the power switch off.

    2. B003XPWC01
      *a

      Front view of wire harness connector

      (to skid control ECU assembly)

      Disconnect the A24 skid control ECU assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A24-24 (STP2) - Body ground Brake pedal released Below 1.5 V

    4. Connect the A24 skid control ECU assembly connector.

      Result
      Proceed to
      OK
      NG

    NG

    CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU)) Click here

    OK

  7. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - REAR COMBINATION LIGHT ASSEMBLY LH)


    1. Turn the power switch off.

    2. Disconnect the A24 skid control ECU assembly connector.

    3. Disconnect the Q43 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
      A24-24 (STP2) or Q43-2 (STP) - Body ground Brake pedal depressed 11 to 14 V

    5. Connect the Q43 rear combination light assembly LH connector.

    6. Connect the A24 skid control ECU assembly connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE REAR COMBINATION LIGHT ASSEMBLY LH Click here

    NG

  8. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - REAR COMBINATION LIGHT ASSEMBLY RH)


    1. Turn the power switch off.

    2. Disconnect the A24 skid control ECU assembly connector.

    3. Disconnect the Q5 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
      A24-24 (STP2) or Q5-2 (STP) - Body ground Brake pedal depressed 11 to 14 V

    5. Connect the Q5 rear combination light assembly RH connector.

    6. Connect the A24 skid control ECU assembly connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE REAR COMBINATION LIGHT ASSEMBLY RH Click here

    NG

  9. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - CENTER STOP LIGHT ASSEMBLY)


    1. Turn the power switch off.

    2. Disconnect the A24 skid control ECU assembly connector.

    3. Disconnect the Q8 center stop light assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A24-24 (STP2) or Q8-1 (B) - Body ground Brake pedal depressed 11 to 14 V

    5. Connect the Q8 center stop light assembly connector.

    6. Connect the A24 skid control ECU assembly connector.

      Result
      Result Proceed to
      OK A
      NG (w/ Vehicle proximity notification system) B
      NG (w/o Vehicle proximity notification system) C

    A

    REPLACE CENTER STOP LIGHT ASSEMBLY Click here

    C

    GO TO STEP 11 Click here

    B

  10. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - VEHICLE APPROACHING SPEAKER CONTROLLER)


    1. Turn the power switch off.

    2. Disconnect the A24 skid control ECU assembly connector.

    3. Disconnect the K145 vehicle approaching speaker controller connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A24-24 (STP2) or K145-2 (STP) - Body ground Brake pedal depressed 11 to 14 V

    5. Connect the K145 vehicle approaching speaker controller connector.

    6. Connect the A24 skid control ECU assembly connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE VEHICLE APPROACHING SPEAKER CONTROLLER Click here

    NG

  11. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU))


    1. Turn the power switch off.

    2. Disconnect the A24 and A25 skid control ECU assembly connector.

    3. Remove the stop light relay (semiconductor power integration ECU).

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1D-10 (STP) - A25-25 (STP) Always Below 1 Ω
      1F-9 (OUT) - A24-24 (STP2) Always Below 1 Ω
      1F-9 (OUT) or A24-24 (STP2) - Body ground Always 10 kΩ or higher

    5. Install the stop light relay (semiconductor power integration ECU).

    6. Connect the A24 and A25 skid control ECU assembly connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU) Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  12. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU))


    1. Turn the power switch off.

    2. Disconnect the A24 skid control ECU assembly connector.

    3. Remove the stop light relay (semiconductor power integration ECU).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A24-24 (STP2) or 1F-9 (OUT) - Body ground Brake pedal released Below 1.5 V

    5. Install the stop light relay (semiconductor power integration ECU).

    6. Connect the A24 skid control ECU assembly connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU) Click here

    NG

  13. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - REAR COMBINATION LIGHT ASSEMBLY LH)


    1. Turn the power switch off.

    2. Disconnect the A24 skid control ECU assembly connector.

    3. Disconnect the Q43 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
      A24-24 (STP2) or Q43-2 (STP) - Body ground Brake pedal released Below 1.5 V

    5. Connect the Q43 rear combination light assembly LH connector.

    6. Connect the A24 skid control ECU assembly connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE REAR COMBINATION LIGHT ASSEMBLY LH Click here

    NG

  14. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - REAR COMBINATION LIGHT ASSEMBLY RH)


    1. Turn the power switch off.

    2. Disconnect the A24 skid control ECU assembly connector.

    3. Disconnect the Q5 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
      A24-24 (STP2) or Q5-2 (STP) - Body ground Brake pedal released Below 1.5 V

    5. Connect the Q5 rear combination light assembly RH connector.

    6. Connect the A24 skid control ECU assembly connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE REAR COMBINATION LIGHT ASSEMBLY RH Click here

    NG

  15. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - CENTER STOP LIGHT ASSEMBLY)


    1. Turn the power switch off.

    2. Disconnect the A24 skid control ECU assembly connector.

    3. Disconnect the Q8 center stop light assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A24-24 (STP2) or Q8-1 (B) - Body ground Brake pedal released Below 1.5 V

    5. Connect the Q8 center stop light assembly connector.

    6. Connect the A24 skid control ECU assembly connector.

      Result
      Result Proceed to
      OK A
      NG (w/ Vehicle proximity notification system) B
      NG (w/o Vehicle proximity notification system) C

    A

    REPLACE CENTER STOP LIGHT ASSEMBLY Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    B

  16. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - VEHICLE APPROACHING SPEAKER CONTROLLER)


    1. Turn the power switch off.

    2. Disconnect the A24 skid control ECU assembly connector.

    3. Disconnect the K145 vehicle approaching speaker controller connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A24-24 (STP2) or K145-2 (STP) - Body ground Brake pedal released Below 1.5 V

    5. Connect the K145 vehicle approaching speaker controller connector.

    6. Connect the A24 skid control ECU assembly connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE VEHICLE APPROACHING SPEAKER CONTROLLER Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  17. CHECK WIRE HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU))


    1. Turn the power switch off.

    2. Remove the stop light relay (semiconductor power integration ECU).

    3. Disconnect the A25 skid control ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A25-31 (STPO) or 1D-3 (ACC) - Body ground Always 10 kΩ or higher

    5. Connect the A25 skid control ECU assembly connector.

    6. Install the stop light relay (semiconductor power integration ECU).

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  18. INSPECT STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU)


    1. Turn the power switch off.

    2. Inspect the stop light relay (semiconductor power integration ECU).

      Click here

      OK
      The stop light relay (semiconductor power integration ECU) is normal.
      Result
      Proceed to
      OK
      NG

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    NG

    REPLACE STOP LIGHT RELAY (SEMICONDUCTOR POWER INTEGRATION ECU) Click here