DYNAMIC RADAR CRUISE CONTROL SYSTEM, Diagnostic DTC:C1A05

DTC Code DTC Name
C1A05 Stop Light Switch Circuit

DESCRIPTION

When the brake pedal is depressed, the stop light switch 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 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 IGN fuse and the stop light switch, and the driving support ECU operates the dynamic radar cruise control.

The brake booster with master cylinder (skid control ECU) receives a signal from the driving support ECU and operates the brake actuator. The brake booster with master cylinder (skid control ECU) operates the brake actuator and at the same time illuminates the stop lights by operating the stop light control relay.

The stop light switch assembly sends a brake pedal operation signal to the driving support ECU.

After receiving the signal, the ECM performs fail-safe control by canceling the cruise control function.

DTC No. DTC Detection Condition Trouble Area
C1A05 Voltages of terminals ST1- and STP- of driving support ECU are both below 1 V for 1 second

  • Stop light switch assembly

  • Stop light switch circuit

  • Driving support ECU

WIRING DIAGRAM

A01JBDHE03

INSPECTION PROCEDURE

Tech Tips

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

PROCEDURE


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


    1. A01JCQ1E10
      Text in Illustration
      *a

      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
      A67-1 (B) - A67-3 (GND) Power switch off 11 to 14 V
      A67-5 (B) - A67-3 (GND) Power switch on (IG) 11 to 14 V
      Standard Resistance
      Tester Connection Condition Specified Condition
      A67-3 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - IG2 RELAY OR BATTERY)

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. A01JCFXE08
      Text in Illustration
      *a

      Component with harness connected

      (Stop Light Switch Assembly)

      Remove the stop light switch assembly Click here.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A67-2 (L) - A67-3 (GND) Power switch off, brake pedal not depressed Below 1 V
      A67-4 (L) - A67-3 (GND) 11 to 14 V
      A67-2 (L) - A67-3 (GND) Power switch off, brake pedal depressed 11 to 14 V
      A67-4 (L) - A67-3 (GND) Below 1 V

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

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


    1. Disconnect the stop light switch assembly connector.

    2. Disconnect the driving support ECU connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Switch Condition Specified Condition
      A67-4 (L) - L60-28 (ST1-) Always Below 1 Ω
      A67-2 (L) - L60-27 (STP-) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Switch Condition Specified Condition
      A67-4 (L) or L60-28 (ST1-) - Body ground Always 10 kΩ or higher
      A67-2 (L) or L60-27 (STP-) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - DRIVING SUPPORT ECU)

    OK

  4. CHECK HARNESS AND CONNECTOR (STOP LIGHT CONTROL RELAY - BODY GROUND)


    1. Disconnect the stop light control relay assembly connector.

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

      Standard Resistance (Check for short)
      Tester Connection Condition Specified Condition
      A67-2 (L) - Body ground Always 10 kΩ or higher
      A67-4 (L) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BODY GROUND)

    OK

    REPLACE DRIVING SUPPORT ECU Click here