Abstract: A redundant power supply circuit in a vehicle electronic control system has a main circuit and a backup circuit which each use a battery source as its primary source, and the main circuit outputs a control signal for activating the backup circuit. A motor driving circuit includes a main monitoring circuit for determining a failure in a main driving circuit for driving a motor, and outputting an abnormal state signal when determining the failure; and a backup driving circuit for outputting a driving signal for driving the motor when receiving the abnormal state signal. In another motor driving circuit, when the motor is driven, the motor is energized through first and second control circuit, each of which can output a signal for driving the motor. When it is determined that the energization is not performed through one of the control circuits, the other control circuit is selected.

Abstract: In a vehicle behavior control system, a failure of a wheel speed sensor is detected by a wheel speed sensor failure detecting device based on the mutual comparison of wheel speeds detected by wheel speed sensors, respectively. When the failure of the wheel speed sensor is detected, a preselected fail-safe operation is carried out by a fail-safe device. A fail-safe operation prohibiting signal is output only for a predetermined time from the establishment of a state in which the operation of a parking brake is detected by a parking brake operation detecting device and a during-traveling signal is output from a during-traveling signal generated device. When the fail-safe operation prohibiting signal is output, the fail-safe operation by the fail-safe device is prohibited by a fail-safe operation prohibiting device.

Abstract: In an anti-lock brake control system, an actuator is controlled based on at least a slip rate determined in a slip rate calculating device and an output from a low-pass filter for filtering a wheel acceleration determined in a wheel acceleration calculating device, thereby switching-over the braking-pressure reducing, maintaining and increasing modes from one to another. The braking pressure-reduction control provided by an operation control device is terminated in response to the wheel acceleration determined in the wheel acceleration calculating device becoming equal to or larger than a preset value. Thus, it is possible to prevent an excessive pressure reduction during an anti-lock brake control on a road surface having a high coefficient of friction.

Abstract: In an anti-lock brake control system for a vehicle, first presumed vehicle speeds are calculated in first vehicle speed calculating devices for every wheel based on wheel speeds detected by wheel speed detecting sections. A second presumed vehicle speed is calculated in a second vehicle speed calculating device based on the value of a lower one of the first presumed vehicle speeds calculated in the first vehicle speed calculating devices corresponding to the left and right rear wheels. A higher one of the first presumed vehicle speeds calculated in each of the first vehicle speed calculating devices and the second presumed vehicle speed calculated in the second vehicle speed calculating device is selected as a presumed vehicle speed corresponding to the wheel in a high-select device. The operations of actuators are controlled based on results of calculation of slip rates of wheels based on presumed vehicle speeds and wheel speeds for every wheel.