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Electronic Power Steering ( EPS ) refers to the modern version of hydraulic power steering and is monitored by a warning light that illuminates during an error. Some cars have electronic power steering gear. A  fast electronic motor inside the rack housing supplies the power assist. The pinion meshes with helical grooves which function as the rack teeth/

  •  A magnet and magnetic sensor on the pinion shaft act as torque sensors, It signals the electronic control module or ECM how much torque is being applied and in which direction. 
  • As torque is applied by turning the steering wheel, the magnet moves. The greater the torque and the farther the magnet moves, the stronger the signal to the ECM. The ECM then sends a varying current to the electric motor, The motor is splined to the ball nut. When the motor runs, the ball nut rotates. The rotation causes balls to run through the grooves in the ball nut and the helical grooves in the rack. 
  • This applies force against one end of the rack. The result is that most of the steering effort is supplied by the electric motor. 

Electronic power steering does not require a hydraulic pump, hoses, a hydraulic piston on the rack, or a sealed rack housing. In addition, if the driver prefers more or less power assist, it can be changed by resetting a selector switch.