Abstract: A system actively monitors the fatigue of gears used in a vehicle drive axle assembly. The system includes a sensor system for detecting a speed of rotation and a torque. The speed of rotation and the torque are indicative of the speed of rotation and the torque on the gears. A microprocessor communicates with the sensor system to gather the speed of rotation and torque information. The microprocessor utilizes the information to actively determine gear fatigue. The microprocessor compares the gear fatigue with a pre-selected threshold gear wear value. If the pre-selected threshold value has been exceeded, the microprocessor provides an output, which preferably notifies the driver of the excessive gear fatigue.