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 assembly. Upon receiving the signal, the driving support ECU assembly cancels speed control by 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 speed control operation is canceled when auxiliary battery voltage is applied to terminal STP-.

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

The brake booster with master cylinder assembly (skid control ECU) receives a signal from the driving support ECU assembly 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 assembly.

After receiving the signal, the ECM performs fail-safe control by canceling cruise control system control of vehicle speed.

DTC No. DTC Detection Condition Trouble Area
C1A05 While power switch is on (IG) and dynamic radar cruise control system is operating, voltages of terminals ST1- and STP- of driving support ECU assembly are both below 1 V for 1 second

  • Stop light switch assembly

  • Stop light switch circuit

  • Driving support ECU assembly

WIRING DIAGRAM

A0041TXE01

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 POWER SOURCE)


    1. A0042O5E69
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the stop light switch assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A26-1 (B) - A26-3 (GND) Power switch off 11 to 14 V
      A26-5 (B) - A26-3 (GND) Power switch ON 11 to 14 V
      Standard Resistance
      Tester Connection Condition Specified Condition
      A26-3 (GND) - Body ground Always Below 1 Ω

    NG

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

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. Inspect the stop light switch assembly Click here.


    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

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


    1. Disconnect the driving support ECU assembly connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      L54-27 (STP-) - A26-2 (L) Always Below 1 Ω
      L54-28 (ST1-) - A26-4 (L) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      L54-27 (STP-) or A26-2 (L) - Body ground Always 10 kΩ or higher
      L54-28 (ST1-) or A26-4 (L) - Body ground Always 10 kΩ or higher

    NG

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

    OK

  4. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BODY GROUND)


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

      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A26-2 (L) - Body ground Always 10 kΩ or higher
      A26-4 (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 ASSEMBLY Click here