Vehicle Preparation

1. Check and verify if vehicle is equipped with original equipment (O.E.), type, size and brand wheels and tires. If non-original equipment (O.E.) wheels and or tires are installed, it may be necessary to substitute original equipment (O.E.) level tire/wheel assemblies for diagnosis.
2. Check and set tire pressure.
3. Unlock the front hubs and back up approximately 20 feet to make sure of hub disengagement if the vehicle is a 4x4.
4. Remove any externally mounted accessories such as luggage racks, or magnetic base antenna, etc., which may cause wind noise that interferes with NVH diagnosis.
5. A tachometer should be used as noted above.
6. Note the fuel level. Some vehicles change in their response to various excitations when the fuel level changes. If the customer mentions that the concern does not occur all the time, this might be a factor.
7. Try to duplicate the conditions with the customer present, particularly the speed and throttle operation. It is not uncommon to find concerns which the customer didn't notice so it is important to identify the concern causing the complaint.