Apparatus for stabilizing power steering for temperature effects

A hydraulically assisted power steering apparatus (10) subject to variance in steering effort due to temperature change is compensated to give consistent response at all temperatures. A hydraulic control valve (16) is coupled to an electromagnetic device (92) which controls the steering effort as a function of energization current. The current is adjusted in accordance with temperature to compensate for temperature changes. A microcomputer control unit (178) stores empirical data relating to the effect of temperature on steering effort and calculates the current adjustment necessary for any measured apparatus temperature. In one embodiment, the temperature is not measured directly but is derived from the deviation of energization current from the theoretical desired current, which deviation is a function of temperature. The effect of voltage variations is also compensated for.