Method for monitoring the performance of a drive line of a vehicle

The subject invention generally relates to a method for monitoring performance of a drive line of a vehicle during driving of the vehicle. A method for monitoring the performance of a drive line of a vehicle during driving of the vehicle is disclosed. A sensor is mounted in a non-contacting relationship on a component of the vehicle for detecting acoustic energy present in the drive line of the vehicle. The acoustic energy is compared to either a predetermined operating limit or developed performance tolerances both of which represent limitations to ideal performance of the drive line. In a further embodiment, the method includes detecting a measurable quantity at the drive line, generating successive signals representative of this quantity, and developing a tolerance from the successive signals. A comparison of a subsequent signal to a previous signal is conducted to determine if the subsequent signal is outside the tolerance. Finally, a further embodiment detects frequencies of rotation at the ends of the drive line during operation of the drive line. This embodiment compares the frequencies of rotation to establish a differential that is indicative of the performance of the drive line.