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Noise, Vibration and Harshness - Noise,
Vibration and Harshness (NVH)
Description and Operation
Noise, vibration and harshness (NVH) is becoming more important as vehicles become
more sophisticated and passenger comfort levels increase. This section is designed to aid in
the diagnosis and testing and repair of NVH concerns.
Noise is defined as sounds not associated with the operation of passenger compartment
equipment that interface with customer satisfaction.
Vibration is defined as impulses felt by the customer that are not caused by road surface
changes.
Harshness is a ride quality issue where the customer feels that the vehicle response to
the road surface is sharply transmitted to the customer.
Diagnostic Theory
Diagnosis is more than just following a series of interrelated steps in order to find the
solution to the specific condition. It is a way of looking at systems that are not functioning
the way they should and finding out why. Also it is knowing how the system should work
and whether it is working correctly.
There are basic rules for diagnosis. If these rules are followed, the cause of the condition is
usually found the first time through the system.
Know the System
Know how the parts go together.
Know how the system operates as well as its limits and what happens when the system
goes wrong.
Sometimes this means checking the system against one that is known to be working
correctly.
Know the History of the System
A clue in any one of these areas may save time:
How old or new is the system?
What kind of treatment has it had?
Has it been serviced in the past in such a manner that might relate to the present
condition?
What is the service history?
Know the History of the Condition
Did it start suddenly or appear gradually?
Was it related to some other occurrence such as a collision or previous part replacement?
Know how the condition made itself known; it may be an important clue to the cause.
Know the Probability of Certain Conditions Developing
Look for the simple rather than the complex.
For example:
-
Electrical conditions usually occur at connections rather than components.
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An engine no-start is more likely to be caused by a loose wire or small adjustment
rather than a sheared-off camshaft.
Know the difference between impossible and improbable. Certain failures in a system can
be improbable but still happen.
New parts are just that, new. It does not mean they are always good functioning parts.
Transit/Tourneo Connect 2002.5 (06/2002-)
http://vnx.su
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