The method consists in: determining in which actually sector the booster motor is located, a sector of the booster motor being defied by two successive poles; determining a relative angle position of the steering wheel in relation to the booster motor; identifying a sector, known as neutral, in which the booster motor is located when the rotation speeds of the rear wheels, i.e. right and left of the vehicle, are equal; determining an angle offset of the steering wheel corresponding to a neutral angle position of the steering wheel; determining an absolute angle position of the steering wheel which is equal to the difference between the relative angle position of the steering wheel and the offset angle thereof.