Traction Control System (TCS) Operation

1. NORMAL MODE 

Fig 1: Normal Mode

Courtesy of HYUNDAI MOTOR CO.

• In the normal driving condition, TC valve (normally open) is the passage between the master cylinder and the each wheel cylinder.
• When brake pedal is applied, brake pressure is delivered to the wheel cylinders via NO-TC valve and all solenoid valves inside the hydraulic unit are deactivated.
• In case of TCS malfunction it does not affect brake operation.

2. PRESSURE INCREASE MODE 

Fig 2: Pressure Increase Mode

Courtesy of HYUNDAI MOTOR CO.

• If a front wheel spin is detected, TCS begins a brake control to decrease a wheel spin.
• Hydraulic shuttle valve (HSV) is opened.

  Brake fluid is supplied from the master cylinder by motor operation to the spin wheel via HSV.

• TC valve is closed (ON).

  Brake pressure generated from motor pump is delivered only to the front wheel.

• Inlet valve remains open to deliver the brake pressure generated from motor pump to the spinning wheels.

3. PRESSURE DUMP MODE 

Fig 3: Pressure Dump Mode

Courtesy of HYUNDAI MOTOR CO.

• When the wheel deceleration is under the threshold and the wheel spin is reduced under a slip threshold, applied brake pressure is reduced to get a optimum traction force.
• Outlet valve is open to release the brake pressure and inlet valve is closed to block the pressure increase from the motor pump.
• Hydraulic shuttle valve (HSV) remains opened, TC valve is ON.
• Motor is ON, to dump the brake fluid being released from the lock-up wheel.

4. PRESSURE HOLD MODE 

Fig 4: Pressure Hold Mode

Courtesy of HYUNDAI MOTOR CO.