The Downhill Brake Control (DBC) function helps the driver control the vehicle when going down a steep hill. When a vehicle goes down hill, pushing the DBC switch enables the car to keep its vehicle's speed at a constant value without operating the brake pedal. The DBC function is operated when the vehicle is on the decline and its velocity is under the predetermined speed.
The Hill start Assist Control (HAC) function helps the vehicle not sleep when start up on a steep hill. The HAC function is operated when the vehicle is on the decline and brake lamp is illuminated when the HAC is operating.
The HECU monitors the brake lamp relay for normal operation. If there is an open or a short in the relay circuit, this DTC is set.
Item | Detecting Condition | Possible cause |
DTC Strategy |
•
Voltage Monitoring | 1. Open or short in the brake lamp relay(DBC relay) circuit 2. Faulty brake lamp relay(DBC relay) |
Monitoring Period |
•
When brake lamp relay drive OFF - If the monitor of Brake Lamp Drive is ON for 500ms, The failure is recognized - If the monitor of Brake Lamp Relay is different from BLS signal for 3sec, The failure is recognized
•
When brake lamp relay drive ON - If the monitor of Brake Lamp Drive is OFF for 500ms, The failure is recognized - If the monitor of Brake Lamp Relay is OFF for 500ms, The failure is recognized | |
Fail Safe |
•
Inhibit the DBC control and allow the ABS/EBD/ESP(ESC) control
•
The DBC warning lamp is activated |
