Inspection and Verification (Start Testing Here)

1. Verify the customer's concern by operating the vehicle to duplicate the condition.
2. Visually inspect the vehicle to determine any obvious cause of the concern(s).
3. If the inspection reveals obvious concern(s) that can be readily identified, service as required.
4. If the concern(s) remains after the inspection, determine the symptoms(s) and go to the Symptom Chart. Symptom Related Diagnostic Procedures

How to Use The Diagnostic Procedures
- Noise, vibration and harshness concerns have become more important as vehicles have become more sensitive to these conditions. This is designed to aid in identifying these situations.
- This provides diagnostic procedures based on symptom. If the condition occurs at high speed, for instance, the most likely place to start is under High Speed Shake in the Symptom Chart.
- The Road Test procedure details how to sort the conditions into categories and distinguish a vibration from a shake.
- Following the Road Test procedure, a series of Road Test Quick Checks is provided to make sure that a cause is either pinpointed or eliminated.
- Use Vehicle Road Test Evaluation form, following the Road Test procedure steps, to record the vehicle road test.
- Refer to the Glossary of Terms to become familiar with the terms.
- Name the condition, go to the appropriate system and locate the proper diagnosis. When the condition is identified, the job is partly done.
- Follow the diagnostic procedure.
- Quick checks are described within the step, while more involved tests and adjustments are described in adjustments.
- Always follow each step exactly and make notes along the way to recall important findings.






Customer Interview
The road test and customer interview (if available) provide information that will help identify the concern and will provide direction to the correct starting point for diagnosis. Use the Customer Concern Evaluation form to record customer concerns.

Identifying the Condition
Noise, Vibration and Harshness (NVH) usually occur in five areas:
- tires
- engine accessories
- suspension
- driveline
- brakes

It is important, therefore, that an NVH concern be isolated into its specific area as soon as possible. The easiest and quickest way to do this is to perform the Road Test procedure. Road Test