The method consists in: (A) determining in which actual sector (tr_engine) the booster motor is located, a sector of the booster motor being defined by two successive poles; determining a relative angle position (Angle_steerwh_rel) of the steering wheel in relation to the booster motor; (B, C, D) identifying a sector, known as neutral (tr_engine_neutral), in which the booster motor is located when the rotation speeds of the rear wheels, i.e. right (v rear R) and left (v rear L) of the vehicle, are equal; (E) determining an angle offset (angle_offset) of the steering wheel corresponding to a neutral angle position of the steering wheel; determining an absolute angle position (angle_steerwh_absolute) of the steering wheel which is equal to the difference between the relative angle position (angle_steerwh_rel) of the steering wheel and the offset angle (angle_offset) thereof.