Road Test Quick Checks

1. 24-80 kph (15-50 mph): With light acceleration, a moaning noise is heard and possibly a vibration is felt in the floorpan. It is usually worse at a particular engine speed and at a particular throttle setting during acceleration at that speed. It may also produce a moaning sound, depending on what component is causing it. Refer to Tip-In Moan. Symptom Related Diagnostic Procedures
2. High speed: With slow acceleration and deceleration, a shake is sometimes noticed in the steering wheel/column, seats, floorpan, trim panels or front end sheet metal. It is a low frequency vibration (around 9-15 cycles per second). It may or may not be increased by applying brakes lightly. Refer to High Speed Shake. Symptom Related Diagnostic Procedures
3. High speed: A vibration is felt in the floorpan or seats with no visible shake, but with an accompanying sound or rumble, buzz, hum, drone or booming noise. Coast with clutch depressed or transmission range selector in NEUTRAL and engine idling. If vibration is still evident, it may be related to wheels , tires, brake rotors, hubs or bearings. Refer to High Speed Shake. Symptom Related Diagnostic Procedures
4. High speed: A vibration is felt whenever the engine reaches a particular rpm. It will disappear in neutral coast. The vibration can be duplicated by operating the engine at the problem rpm while the vehicle is sitting still. It can be caused by any component, from the accessory drive belts to the clutch or torque converter, which turns at engine speed when the vehicle is stopped. Refer to Engine Accessory Vibration. Symptom Related Diagnostic Procedures
5. Turning: Noise and vibration, clicking, popping or grinding noises heard while turning may be due to the following:
a. Cut or damaged front wheel driveshaft joint boot resulting in inadequate or contaminated lube fill in outboard, front wheel driveshaft joint or front wheel driveshaft and joint .
b. Other component contacting halfshaft assembly.
c. Worn, damaged or improperly installed wheel bearing.
d. Worn, contaminated, or dry inboard CV joint stub shaft pilot bearing housing or outboard CV joints.

Road Conditions
The road is an important factor in the road test and a smooth asphalt road that allows driving over a range of speeds is best. The brushed concrete road surface found on many expressways and the coarse aggregate sometimes found in concrete can mask many vehicle noises and make diagnosis difficult.

If the customer complains of a noise or vibration on a particular road and only on a particular road, the source of the problem may be the road surface. If possible, try to test on the same type of surface. This is the only case where a smooth asphalt road may not be the best.

Vehicle Preparation
1. Check and verify if vehicle is equipped with original equipment, type, size and brand wheels and tires. If non-original equipment wheels and or tires are installed, it may be necessary to substitute original equipment level tire/wheel assemblies for diagnosis.
2. Check and set tire pressure.