The ESC is the acronym for Electronic Stability control. The ESC is a braking system that combines the functions of a brake servo unit and the ABS (Antilock Braking System) equipment including ESP (Electronic Stability Program). The ESC is a technology that improves the safety of a vehicle's stability by detecting and reducing loss of traction. When ESC detects loss of a steering control, it automatically applies the brakes to help steer the vehicle where the driver intends to go. Braking is automatically applied to wheels individually. The HECU supplies battery power to all solenoid valves with a valve relay which is controlled by the Electronic Control Unit(ECU). The valve relay and all solenoid valves are installed inside the HECU ( Hydraulic and Electronic Control Unit ).