Test Notes

Road Test
A gear-driven unit, especially an automotive drive axle, will produce a certain amount of noise. Some noise is acceptable and may be audible at certain speeds or under various driving conditions, as on a newly paved blacktop road. The slight noise is in no way detrimental to the operation of the rear axle and must be considered normal.

NOTE: It is important that the rear axle noise be evaluated in direct drive as well as overdrive.

The road test and customer interview (if available) provide information needed to identify the condition and give direction to the correct starting point for diagnosis.

1. Make notes throughout diagnosis routine. Use a road test form that includes space for comments. Make sure to write down even the smallest bit of information because it may turn out to be the 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 proper section of the diagnosis procedure. Perform the Road Test Quick Checks more than once to make sure they are providing a valid result. Remember, the Road Test Quick Checks may not tell where the concern is, but they will tell where it is not.
4. Do not touch 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 condition was first observed. Adjusting tire pressures, vehicle load or making other adjustments may reduce the condition's intensity to a point where it cannot be identified clearly. It may also introduce something new into the system, prohibiting 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 bolts or bright spots where components may be rubbing against each other. Check the luggage compartment for unusual loads.