Abstract: A torque distribution control device for a four-wheel drive vehicle is disclosed having a torque distribution device for distributing the drive power transmitted from an engine to either of the front wheels or the rear wheels as prime drive wheels, to other wheels as sub-drive wheels. In the control device, abnormality judgment means judges whether or not an abnormality is involved in wheel speed signals which are input from wheel speed sensors associated respectively with the front and rear wheels. Means is further provided for altering a normal-state method of calculating a command torque which is applied to the torque distribution device to vary the drive power transmitted to the sub-drive wheels, to an abnormal-state method of calculating the command torque based on data which does not include one wheel speed signal involving the abnormality when the same occurs with one of the wheel speed signals, whereby the vehicle is enabled to continue the four-wheel drive even when the abnormality occurs.

Abstract: An abnormality detection apparatus, which reduces erroneous detection of an open abnormality of a relay, includes a microcomputer that activates the relay and determines whether the output voltage of the relay is less than a threshold value. When the output voltage is less than the threshold value, the microcomputer repeats the activation of the relay and the determination. The detection unit detects the occurrence of an open abnormality when the repetition number exceeds two.

Abstract: A calculator for calculating an opened amount of a throttle valve with high accuracy regardless of voltage fluctuation and noise. The calculator includes a valve sensor for detecting the opened amount of the throttle valve to generate a detection voltage. A memory stores an initial zero point detection value. A calculation circuit obtains the difference between the detection voltage and the initial zero point detection value and calculates the opened amount of the throttle valve with the difference. When a plurality of detection voltages that are less than the initial zero point detection value are generated, the calculation circuit calculates a new zero point detection value that is greater than a smallest one of the plurality of detection voltages by a predetermined value and updates the initial zero point detection value with the new zero point detection value.