Inspection and Verification (Start Testing Here)

NOISE, VIBRATION AND HARSHNESS
1. Verify the customer concern by operating the system.
2. Visually inspect for obvious signs of mechanical or electrical damage.
3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
4. If the concern is not visually evident, verify the symptom and refer to the Symptom Chart. Symptom Related Diagnostic Procedures

How To Use This Diagnostic Procedure
- Noise, Vibration and Harshness (NVH) concerns have become more important as vehicles have become more sensitive to these vibrations.
- The section 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.
- The road test procedure will tell how to sort the conditions into categories and how to tell a vibration from a shake.
- A series of Road Test Quick Checks is provided to make sure that a cause is either pinpointed or eliminated.
- Name the condition, proceed to the appropriate system and locate the correct 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 in General Procedures.
- Always follow each step exactly and make notes to recall important findings later.

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.

Identify the Condition NVH usually occurs in four areas:
- tires
- engine accessories
- suspension
- driveline

It is important, therefore, that a NVH concern be isolated into its specific area(s) as soon as possible. The easiest and quickest way to do this is to carry out the Road Test. Road Test
To assist in the diagnosis and testing procedure(s), use a suitable approved NVH diagnosis tester.