DYNAMIC RADAR CRUISE CONTROL SYSTEM, Diagnostic DTC:C1A4B

DTC Code DTC Name
C1A4B Stop Light Relay Circuit

DESCRIPTION

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

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

Either of the following conditions is met:


  • When the vehicle speed is approximately 50 km/h or more, the cruise control switch (ON-OFF button) is on, 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 vehicle speed is approximately 50 km/h or more, the cruise control switch (ON-OFF button) is on, the IG1 terminal voltage is between 11 and 14 V and the stop light illumination output signal (STPO) is not output, the signals received at terminals STP and STP2 are different for 0.3 seconds or more.

  • Lighting system

  • Brake actuator assembly (skid control ECU)

  • Semiconductor PWR integration ECU

  • Harness or connector

WIRING DIAGRAM

A001HN5E02

CAUTION / NOTICE / HINT

Note


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

  • When this DTC is output, a malfunction in the lighting system is suspected. Check if the lighting system is functioning normally.

    Click here

PROCEDURE


  1. INSPECT ENGINE START


    1. Depress the brake pedal, push the engine switch and check that the engine starts.

      OK
      The engine starts.
      Result
      Proceed to
      OK
      NG

    NG

    GO TO SFI SYSTEM for 2GR-FSE: Click here
    GO TO SFI SYSTEM for 4GR-FSE (w/ Canister Pump Module): Click here
    GO TO SFI SYSTEM for 4GR-FSE (w/o Canister Pump Module): Click here

    OK

  2. 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.
      Result
      Proceed to
      OK
      NG

    NG

    GO TO LIGHTING SYSTEM Click here

    OK

  3. INSPECT SEMICONDUCTOR PWR INTEGRATION ECU


    1. Using a voltmeter, check the signal reading of the semiconductor PWR integration ECU.

      Click here

      OK
      Output signal reading is normal.
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT SEMICONDUCTOR PWR INTEGRATION ECU (RESULTS OF SIGNAL READING CHECK) Click here

    OK

  4. CHECK HARNESS AND CONNECTOR (STPO TERMINAL VOLTAGE)


    1. A001L5DC02
      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly (Skid Control ECU))

      Turn the engine switch off.

    2. Disconnect the A15 brake actuator assembly (skid control ECU) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A15-31 (STPO) - Body ground Always 11 to 14 V

    4. Connect the A15 brake actuator assembly (skid control ECU) connector.

      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) - SEMICONDUCTOR PWR INTEGRATION ECU) Click here

    OK

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


    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 control relay (STOP LP) ON or OFF Stop lights come on

      Chassis > ABS/VSC/TRC > Active Test
      Active Test Display
      Stop Light Relay
      Data List Display
      Stop Light Relay Output

    2. According to the display on the GTS, read the Data List item Stop Light Relay Output.


      Chassis > ABS/VSC/TRC > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Stop Light Relay Output Stop light control relay (STOP LP) output ON or OFF

      ON: Relay output on (Stop light on)

      OFF: Relay output off (Stop light off)

      		 -

    3. Check that the Data List item Stop Light Relay Output changes between ON and OFF and the stop lights turn on and off according to the operation of the Active Test.

      Result
      Result Proceed to
      The Data List item Stop Light Relay Output does not change between ON and OFF and the stop lights do not turn ON and OFF according to the operation of the Active Test. A
      The Data List item Stop Light Relay Output changes between ON and OFF but the stop lights do not turn ON and OFF according to the operation of the Active Test. B

    B

    CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) - SEMICONDUCTOR PWR INTEGRATION ECU) Click here

    A

  6. INSPECT BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU)


    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 control relay (STOP LP) ON or OFF Stop lights come on

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

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

      Tech Tips

      Do not disconnect the semiconductor PWR integration ECU connector.

      Standard Voltage
      Tester Connection Condition Specified Condition
      2D-3 (ACC) - Body ground

      Engine switch on (IG)

      (Active test OFF)

      		 11 to 14 V
      2D-3 (ACC) - Body ground

      Engine switch on (IG)

      (Active test ON)

      		 Below 1.5 V
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE SEMICONDUCTOR PWR INTEGRATION ECU Click here

    NG

    REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) for RHD: Click here

  7. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) - SEMICONDUCTOR PWR INTEGRATION ECU)


    1. Turn the engine switch off.

    2. Disconnect the A15 brake actuator assembly (skid control ECU) connector.

    3. Disconnect the 2F semiconductor PWR integration ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A15-22 (STP2) - 2F-9 (OUT) Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) for RHD: Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  8. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) - SEMICONDUCTOR PWR INTEGRATION ECU)


    1. Turn the engine switch off.

    2. Disconnect the A15 brake actuator assembly (skid control ECU) connector.

    3. Disconnect the 2D semiconductor PWR integration ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A15-31 (STPO) - 2D-3 (ACC) Always Below 1 Ω
      A15-31 (STPO) or 2D-3 (ACC) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE SEMICONDUCTOR PWR INTEGRATION ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR