Noise, Vibration and Harshness

Noise, vibration and harshness (NVH in engineering shorthand) is becoming more and more important as the vehicles are becoming more sensitive to these vibrations. This section is designed to give a working knowledge of the process of diagnosing noise and vibration situations. It is divided into several sections based on the description of the condition. If the condition occurs at high speed, for instance, the most likely place to start is under High Speed Shake. The Road Test Section will tell how to sort out the conditions into categories and how to tell a vibration from a shake. It will give a few hints on quick checks to make sure that a cause is either pinpointed or eliminated.

Become familiar with the terms. Use the Glossary section to find the descriptive name of conditions not encountered before. After naming it, proceed to the section identifying the condition, and locate the proper diagnosis section. Remember, just by beginning at a particular point, most other systems in the vehicle have been eliminated. When the proper section is identified, the job is partly done. Follow the steps within the section. Quick Checks are described within the step, while more involved tests and adjustments are found in Service and Adjustment. Always follow each step exactly and make notes along the way to recall important findings.