DYNAMIC RADAR CRUISE CONTROL SYSTEM, Diagnostic DTC:C1A05, C1A4B

DTC Code DTC Name
C1A05 Stop Light Switch Circuit
C1A4B Stop Light Relay Circuit

DESCRIPTION

The skid control ECU receives a signal from the driving support ECU and operates the brake actuator. The skid control ECU operates the brake actuator and at the same time illuminates the stop light by operating the stop light control relay.

When the brake pedal is depressed, the stop light switch assembly sends a signal to the driving support ECU. Upon receiving the signal, the driving support ECU cancels the dynamic radar cruise control system. Even if there is a malfunction in the stop light switch signal circuit while the cruise control is operating, normal driving is maintained due to the fail-safe function. Dynamic radar cruise control is canceled when positive battery voltage is applied to terminal STP-.

When the brake pedal is released, positive voltage is applied to terminal ST1- of the driving support ECU through the ECU IG2 fuse and the stop light switch assembly, and the driving support ECU operates the dynamic radar cruise control.

DTC No. DTC Detection Condition Trouble Area
C1A05 When the power switch is turned on (IG) and the cruise control main switch is turned on, the voltage at terminals ST1- and STP- of the driving support ECU are both below 1 V for 1 second.

  • Stop light switch assembly

  • Stop light switch circuit

  • Driving support ECU
C1A4B This trouble code is output when the driving support ECU detects the stop light control relay error signal from the skid control ECU for 1 second while the dynamic cruise control is operating.

  • Stop light control relay

  • Stop light control relay circuit

  • Skid control ECU

  • Driving support ECU

WIRING DIAGRAM

A01NMYXE02

INSPECTION PROCEDURE

Note

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

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
      Condition Illumination Condition
      Brake pedal depressed ON
      Brake pedal released OFF

    NG

    GO TO LIGHTING SYSTEM Click here

    OK

  2. READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH ASSEMBLY)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Radar Cruise / Data List.

    5. Check the Data List for proper functioning of the stop light switch.

      Radar Cruise
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Stop Light SW 1 (M CPU) Stop light switch (Main-CPU) signal/ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

      		 -
      Stop Light SW 1 (S CPU) Stop light switch (Sub-CPU) signal/ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

      		 -
      Stop Light SW 2 (M CPU) Stop light switch (Main-CPU) signal/ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

      		 -
      OK
      Display changes according to brake pedal operation described in above table.

    NG

    CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY POWER SOURCE) Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU)


    1. Disconnect the stop light switch assembly connector.

    2. Disconnect the skid control ECU connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A108-2 (L) - A91-16 (STP1) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A108-2 (L) or A91-16 (STP1) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SKID CONTROL ECU)

    OK

  4. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - SKID CONTROL ECU)


    1. Disconnect the stop light control relay connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A52-1 (OUT) - A90-14 (STP2) Always Below 1 Ω
      A52-4 (ESSI) - A92-11 (EX0) Always Below 1 Ω
      A52-5 (STP) - A91-16 (STP1) Always Below 1 Ω
      A52-9 (ACC) - A91-4 (STP0) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A52-1 (OUT) or A90-14 (STP2) - Body ground Always 10 kΩ or higher
      A52-4 (ESSI) or A92-11 (EX0) - Body ground Always 10 kΩ or higher
      A52-5 (STP) or A91-16 (STP1) - Body ground Always 10 kΩ or higher
      A52-9 (ACC) or A91-4 (STP0) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. INSPECT STOP LIGHT CONTROL RELAY


    1. Inspect the stop light control relay Click here.


    NG

    REPLACE STOP LIGHT CONTROL RELAY Click here

    OK

  6. REPLACE SKID CONTROL ECU


    1. Replace the skid control ECU Click here.


    NEXT

  7. CHECK FOR DTCs (DTC C1A05 OR C1A4B)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Clear the DTCs Click here.

    4. Perform the following to make sure that the DTC detection conditions are met.

      Tech Tips

      If the detection conditions are not met, the malfunction cannot be detected.


      1. Drive the vehicle at a speed for which radar cruise control operation is possible.

      2. Turn the cruise control system on using the cruise control main switch (ON-OFF button).

      3. Push the cruise control main switch to -/SET to begin control of vehicle speed using the cruise control system.

    5. Enter the following menus: Powertrain / Radar Cruise / DTC.

    6. Check for DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC C1A05 or C1A4B is output B

    B

    REPLACE POWER MANAGEMENT CONTROL ECU Click here

    A

    END

  8. REPLACE POWER MANAGEMENT CONTROL ECU


    1. Replace the power management control ECU Click here for LHD, Click here for RHD).


    NEXT

  9. CHECK FOR DTCs (DTC C1A05 OR C1A4B)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Clear the DTCs Click here.

    4. Perform the following to make sure that the DTC detection conditions are met.

      Tech Tips

      If the detection conditions are not met, the malfunction cannot be detected.


      1. Drive the vehicle at a speed for which radar cruise control operation is possible.

      2. Turn the cruise control system on using the cruise control main switch (ON-OFF button).

      3. Push the cruise control main switch to -/SET to begin control of vehicle speed using the cruise control system.

    5. Enter the following menus: Powertrain / Radar Cruise / DTC.

    6. Check for DTCs.

      Result
      Result Proceed to
      DTC is not output A
      DTC C1A05 or C1A4B is output B

    B

    REPLACE DRIVING SUPPORT ECU Click here

    A

    END

  10. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY POWER SOURCE)


    1. Disconnect the stop light switch assembly connector.

    2. A01NMCNE46
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A108-1 (B) - A108-3 (GND) Power switch off 11 to 14 V
      A108-5 (B) - A108-3 (GND) Power switch on (IG) 11 to 14 V
      Standard Resistance
      Tester Connection Condition Specified Condition
      A108-3 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  11. CHECK STOP LIGHT SWITCH ASSEMBLY


    1. Connect the stop light switch assembly connector.

    2. A01NLW4E48
      Text in Illustration
      *1

      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
      A108-2 (L) - A108-3 (GND) Power switch off, Brake pedal not depressed Below 1 V
      Power switch off, Brake pedal depressed 11 to 14 V
      A108-4 (L) - A108-3 (GND) Power switch on (IG), Brake pedal not depressed 11 to 14 V
      Power switch on (IG), Brake pedal depressed Below 1 V

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

  12. CHECK HARNESS AND CONNECTOR (DRIVING SUPPORT ECU - STOP LIGHT SWITCH ASSEMBLY)


    1. Disconnect the driving support ECU connector.

    2. Disconnect the stop light switch assembly connector.

    3. Disconnect the skid control ECU connector.

    4. Disconnect the stop light control relay connector.

    5. Disconnect the power management control ECU connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      C1-27 (STP-) - A108-2 (L) Always Below 1 Ω
      C1-28 (ST1-) - A108-4 (L) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      C1-27 (STP-) or A108-2 (L) - Body ground Always 10 kΩ or higher
      C1-28 (ST1-) or A108-4 (L) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE DRIVING SUPPORT ECU Click here