Vehicle Preparation

Do not adjust or repair anything until a Road Test and a thorough visual inspection of the vehicle have been performed. Leave the tire pressures and vehicle load just where they were when the customer brought the vehicle in.

Adjusting the pressures, vehicle load, or making some other seemingly minor adjustment may reduce the intensity of the problem to a point where it cannot be identified clearly. It may also add something new to the condition that the customer was not previously aware of, preventing proper diagnosis. Make a visual inspection as part of the preliminary diagnosis routine, writing down anything that does not look right. Note tire pressures, but do not adjust them yet. Note leaking fluids, loose nuts and/or bolts, or bright spots where components may be rubbing against each other. Check the cargo area for unusual loads or damage.

Make notes throughout the diagnosis routine. It will help cover all the bases when starting to add up the clues. Use a photocopy of the NVH Road Test Form. Make sure to write down even the smallest bit of information; it may turn out to be very important.
Perform the Road Test Quick Checks to bring out the problem condition. This will identify the proper section of the diagnosis procedure. Run through the check procedure more than once to be sure you are getting a useable result.