Test Overview

Road Test
NVH diagnosis should always start with the road test. Noise, vibration and harshness (NVH) usually occurs in four areas: tires, engine accessories, suspension or powertrain. 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 a road test.
A gear-driven unit will produce a certain amount of noise. Some noise is acceptable and may be audible at certain speeds or under various driving conditions. The slight noise is in no way detrimental and must be considered normal.
1. Make notes throughout diagnostic routine. It will help cover all bases when starting to add up clues. Use a road test form that includes space for comments. Write down even the smallest bit of information, as it may turn out to be most important.
2. Road test the vehicle, and define the condition by reproducing it several times during the road test.
3. Perform the road test quick checks as soon as the condition is reproduced. This will identify the appropriate diagnostic procedure. Run through the quick checks more than once to make sure they are getting a usable result. Remember, the road test quick checks may not tell where the concern is, but they will tell where it is not.
4. Make a visual inspection as part of the preliminary diagnostic routine, writing down anything that does not look right. Note tire pressures, leaking fluids, loose nuts and/or bolts, or bright spots where components may be rubbing against each other. Check cargo area for unusual loads.