EPS Control Unit

WARNING: This page is about a different car, the 2009 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.

EPS control unit performs an arithmetical operation on data, such as steering wheel turning force (sensor signal) from the torque sensor, vehicle speed signal, etc. Then it generates an optimum assist torque to the EPS motor according to the driving condition.
EPS control unit decreases the output to EPS motor while extremely using the power steering function (e.g., full steering) for protecting EPS motor and EPS control unit (Protect overload status). While activating protect overload status, the assist torque gradually decreases, and the steering wheel turning force becomes heavy. The normal assist torque reactivates by not steering.
In case of an error in the electrical system, the fail-safe function stops output signals to the EPS motor. Then the previous state is changed to the manual steering state.
Self-diagnosis can be done with CONSULT-III.

Fig 1: Identifying EPS Motor And EPS Control Unit

Courtesy of NISSAN MOTOR CO., U.S.A.