DTC C1A05: Stop Light Switch Circuit; DTC C1A4B: Stop Light Relay 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 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 battery voltage is applied to terminal STP-.

When the brake pedal is released, 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 cruise control system control of vehicle speed.

The brake booster with master cylinder (skid control ECU) outputs a stop light operation signal to the stop light control relay. When the brake booster with master cylinder (skid control ECU) detects a malfunction in the circuit related to the stop light, it informs the driving support ECU assembly via CAN communication and stores DTC C1A4B.