A variable transmission-ratio steering apparatus comprises an input shaft
coupled to a steering wheel, an output shaft operatively coupled to
steerable road wheels. The apparatus comprises an electric motor varying a
rotation angle of the output shaft by providing a drive force to the
output shaft, the drive force being decided based on a rotation angle of
the input shaft, a lock member locking the input shaft to the output shaft
in an unlockable manner, and an excitation coil enabling the lock member
to be actuated to unlock a lock between the input and output shafts. The
apparatus further comprises a unit controlling current to be supplied to
the excitation coil and a unit detecting abnormality of the excitation
coil based on both of a command value of current to flow through the
excitation coil and a value of the current actually flowing through the
excitation coil.
