Pre-Diagnostic Checks-NVH

PRELIMINARY DIAGNOSTIC INFORMATION

The first step of NVH diagnosis is accurately interpreting the information recorded by the service writer/advisor regarding the NVH concern. The service writer/advisor must record as much information as possible from the customer. It is important to know if the concern is constant or intermittent, as well as the conditions under which the symptoms occur.

Is the concern related to vehicle speed, engine speed, weather, or temperature?
Does the concern occur when the vehicle is loaded, or driven on a particular surface?
Where is the vibration felt the strongest?
When did the vibration begin?
Are there any related symptoms?

This may require talking to the service writer/advisor and/or reviewing the service history of the vehicle to determine if any other repairs were performed for similar symptoms. Review any Service Bulletins (SBs) to determine if any relate to the symptoms described by the customer.

DUPLICATING THE CONCERN

Always duplicate the concern before attempting to diagnose and correct it. After duplicating the customer concern, verify it is not a normal mode of operation. Never attempt to repair a concern that cannot be duplicated or is considered normal operation.

NOTE:

If possible, have the customer demonstrate the concern. The perception of an NVH concern is subjective and will vary from person to person.

PRE-ROAD TEST INSPECTION

Before performing a road test, it is necessary to perform a pre-road test inspection. Begin with a visual inspection. Carefully inspect the wheels and tires.

Check the tires for:

Tire Inflation pressure
Proper tire type, verify the tires are uniform in size and brand
Properly installed tires and if the tire bead is uniform around the wheel
Abnormal tire wear, such as cupping, flat spots, shoulder wear, feathering, and correct tread groove depth
Damage, cuts, and bulging

Check the wheels for:

Foreign debris, such as mud or ice in the wheels
Deformed or bent wheels
Missing or excessive wheel weights
Lug nuts torqued to specification

Check the vehicle for:

Obvious signs of damaged components
Indications of collision damage
Aftermarket components