Patent ID: 7628260

Claim:
A system for controlling a power train of a vehicle, comprising: a drive unit; a transmission having an input, an output, and a plurality of gears, the output operatively coupled to at least one wheel on the vehicle, the at least one wheel having brakes; a torque converter having an input operatively coupled to the drive unit and an output operatively coupled to the input of the transmission, the torque converter having a lock-up clutch; a lock-up clutch control device operatively connected to the lock-up clutch; an antilock braking system configured to prevent locking of the at least one wheel on the vehicle during application of the brakes to the at least one wheel when the antilock braking system is functioning properly; and a controller configured to determine whether a condition is present in which the antilock braking system is not functioning properly, and upon determination that the antilock braking system is not functioning properly, controlling the lock-up clutch control device to at least partially disengage the lock-up clutch; wherein the plurality of gears include a gear having a lowest gear ratio and a gear having a second to lowest gear ratio, and the controller determines whether the antilock braking system is working properly during a downshift between the gear having the lowest gear ratio and the gear having the second lowest gear ratio in the transmission.