•  The torque sensor, which is located on the shaft of the steering column, detects the steering torque and the steering direction, and outputs the signal to the Electric Power Steering (EPS) control module.

•  The torque sensor is an optical torque sensor which consists of an input shaft disc, output shaft disc, light pipes (light guide), LEDs, and linear array detectors.

•  A semi-transparent planer disc which has slits along its perimeter is located on the input shaft, and another similar disc is located on the output shaft.

•  The input shaft and output shaft are engaged by the torsion bar. When the driver operates the steering wheel, torsion occurs on the torsion bar due to the steering force input to the input shaft and the road surface resistance on the steering gear side.

•  Torsion to the torsion bar causes the input and output shafts to move relative to each other. Due to this, the discs on each shaft also move relative to each other.

•  The slits on each disc are arranged such that no two slits are located in the same position on either disc. This arrangement changes the brightness of the light from the LED which strikes the linear array detection device via the light pipe.

•  The linear array detection device converts the change in brightness to an electrical signal which is output to the EPS control module.

•  The two electrical signals output from the torque sensor are calculated in the EPS control module, and the average is used for various control as the steering torque signal.