Road Test

^ A road test is mandatory for any noise or vibration that is not eliminated by the on-hoist check of chassis components. The NVH Road Test Form is arranged to record the conditions that may be heard or felt during this test.
^ The NVH Road Test Form lists operating conditions or modes in which some axle noises come and go.
^ To perform a good diagnostic check it is important to operate the vehicle in all modes and check off those in which the noise occurs. Write down the speed range at which both noise and vibration occur. On vehicles equipped with overdrive transmissions, evaluate rear axle noise with the transmission in DIRECT DRIVE and not in OVERDRIVE. Transmission noise can be mistaken for rear axle noise when in OVERDRIVE.