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 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 |
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| C1A4B | While power switch is on (IG) and dynamic radar cruise control system is operating, the brake booster with master cylinder assembly (skid control ECU) detects a malfunction in the stop light control relay circuit for 1 second while the dynamic cruise control is operating. |
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