Noise, Vibration and Harshness (NVH)

Slow Acceleration Test

To carry out this test, proceed as follows:

Slowly accelerate to the speed where the reported concern occurs. Note the vehicle speed, and if possible, determine the vibration frequency. Attempt to identify what part of the vehicle the concern is coming from. Attempt to identify the source of the concern. Proceed as necessary.

Heavy Acceleration Test

To carry out this test, proceed as follows:

Accelerate hard from 0-64 km/h (0-40 mph). Decelerate in a lower gear. The concern is torque related if duplicated while carrying out this test. Proceed as necessary.

Neutral Coast Down Speed Test

To carry out this test, proceed as follows:

Drive at a higher rate of speed than where the concern occurred when carrying out the Slow Acceleration Test. Place the transmission in NEUTRAL and coast down past the speed where the concern occurs. The concern is vehicle speed-related if duplicated while carrying out this test. This eliminates the engine or motor as a source. Proceed as necessary.

Steering Input Test

To carry out this test, proceed as follows:

Drive at the speed where the concern occurs, while making sweeping turns in both directions. If the concern goes away or gets worse, the wheel bearings, hubs and tire tread wear are all possible sources. Proceed as necessary.

Brake Test

To carry out this test, proceed as follows:

Warm the brakes by slowing the vehicle a few times from 80-32 km/h (50-20 mph) using light braking applications. At highway speeds of 89-97 km/h (50-60 mph), apply the brake using a light pedal force. Accelerate to 89-97 km/h (55-60 mph). Lightly apply the brakes and slow the vehicle to 30 km/h (20 mph). A brake vibration noise can be felt in the steering wheel, seat or brake pedal. A brake noise can be heard upon brake application and diminish when the brake is released. If the source of the symptom has been identified as a result of this test, proceed to the appropriate brake section(s) for further diagnosis and repair. If the source has not been identified, continue with the road test.

Road Test Over Bumps

To carry out this test, proceed as follows:

Drive the vehicle over a bumpy or rough surface one wheel at a time to determine if the noise is coming from the front or the back and the left or the right side of the vehicle. Proceed as necessary.

Vehicle Cold Soak Procedure

To carry out this procedure, proceed as follows:

Test preparations include matching the customer conditions (if known). If not known, document the conditions. Monitor the vibration/noise duration with a watch for up to 3 minutes. Park the vehicle where testing will occur. The vehicle must remain at or below the concern temperature (if