NVH Condition and Symptom Categories

A good diagnostic process is a logical sequence of steps that lead to the identification of a causal system. Use the condition and symptom categories as follows:
^ Identify the operating condition that the vehicle is exhibiting.
^ Match the operating condition to the symptom.
^ Verify the symptom.
^ Identify which category or system could cause the symptom.
^ Refer to the diagnostic symptom chart that is referred to. Symptom Charts

Operating Condition-Vehicle is Not Moving

1. Static operation
^ Noise occurs during component/system functioning. GO to Symptom Chart- Squeak and Rattle. Squeak and Rattle

2. While cranking
1. Grinding or whine, differential ring gear or starter motor pinion noise. GO to Symptom Chart-Engine Noise/Vibration. Engine Noise/Vibration
2. Rattle. Exhaust hanger, exhaust heat shield or A/C line noise. GO to Symptom Chart-Squeak and Rattle. Squeak and Rattle
3. Vibration. Acceptable condition.

3. At idle
^ Idle noise. GO to Symptom Chart-Idle Noise/Vibration. Idle Noise/Vibration
^ Idle vibration or shake. GO to Symptom Chart-Idle Noise/Vibration. Idle Noise/Vibration

4. During Gear Selection
1. Vehicle parked on a steep incline. Acceptable noise.
2. Vehicle parked on a flat surface. Go to Symptom Chart-Driveline Noise/Vibration. Driveline Noise/Vibration
3. Vehicle with a manual transmission. GO to Symptom Chart-Transmission (Manual) and TransferCase Noise/Vibration. Transmission and Transfer Case Noise/Vibration

Operating Condition-Vehicle is Moving

1. Depends more on how the vehicle is operated
1. Speed related
^ Related to vehicle speed
- Pitch increases with vehicle speed. GO to Symptom Chart-Tire Noise/Vibration. Tire Noise/Vibration
- Noise occurs at specific vehicle speed. A high-pitched noise (whine). GO to Symptom Chart-Driveline Noise/Vibration. Driveline Noise/Vibration
- Loudness proportional to vehicle speed. Low-frequency noise at high speeds, noise and loudness increase with speed. GO to Symptom Chart-Driveline Noise/Vibration. Driveline Noise/Vibration
- A low-pitched noise (drumming). GO to Symptom Chart-Engine Noise/Vibration. Engine Noise/Vibration
- Vibration occurs at a particular speed (mph) regardless of acceleration or deceleration. GO to Symptom Chart-Tire Noise/Vibration. Tire Noise/Vibration
- Noise varies with wind/vehicle speed and direction. GO to Symptom Chart-Air Leak and Wind Noise. Air Leak and Wind Noise

^ Related to engine speed.
- Noise varies with engine rpm. GO to Symptom Chart-Engine Noise/Vibration. Engine Noise/Vibration
- Vibration occurs at a particular speed (mph) regardless of engine speed (rpm).

2. Acceleration
^ Wide open throttle (WOT)
- Engine induced contact between components. Inspect and repair as necessary.
- Noise is continuous throughout WOT. Exhaust system or engine ground out. GO to Symptom Chart-Engine Noise/Vibration. Engine Noise/Vibration

^ Light/moderate acceleration
- Tip-in moan. Engine/exhaust noise. GO to Symptom Chart-Engine Noise/Vibration. Engine Noise/Vibration
- Knock-type noise. GO to Symptom Chart-Engine Noise/Vibration. Engine Noise/Vibration
- Driveline shudder. GO to Symptom Chart-Driveline Noise/Vibration. Driveline Noise/Vibration
- Engine vibration. GO to Symptom Chart-Engine Noise/Vibration.

3. Turning noise. GO to Symptom Chart-Steering Noise/Vibration. Steering Noise/Vibration
4. Braking
^ Clicking sound is signaling Anti-Lock Brake System (ABS) is active. Acceptable ABS sound.
^ A continuous grinding/squeal. GO to Symptom Chart-Brake Noise/Vibration. Brake Noise/Vibration
^ Brake vibration/shudder. GO to Symptom Chart-Brake Noise/Vibration. Brake Noise/Vibration

5. Clutching
^ A noise occurring during clutch operation. GO to Symptom Chart-Transmission (Manual) and Transfer Case Noise/Vibration. Transmission and Transfer Case Noise/Vibration
^ Vibration. GO to Symptom Chart-Transmission (Manual) and Transfer Case Noise/Vibration. Transmission and Transfer Case Noise/Vibration

6. Shifting
^ Noise or vibration condition related to the transmission (automatic). GO to Symptom Chart-Transmission (Automatic) Noise/Vibration. Transmission and Transfer Case Noise/Vibration
^ Noise or vibration related to the transmission (manual). GO to Symptom Chart-Transmission (Manual) and Transfer Case Noise/Vibration. Transmission and Transfer Case Noise/Vibration

7. Engaged in four-wheel drive. GO to Symptom Chart-Transmission (Manual) and Transfer Case Noise/Vibration. Transmission and Transfer Case Noise/Vibration
8. Cruising speeds
^ Accelerator pedal vibration. GO to Symptom Chart-Engine Noise/Vibration. Engine Noise/Vibration
^ Driveline vibration. GO to Symptom Chart-Driveline Noise/Vibration. Driveline Noise/Vibration
^ A shimmy or shake. GO to Symptom Chart-Tire Noise/Vibration. Tire Noise/Vibration

9. Driving at low/medium speeds
^ A wobble or shudder. GO to Symptom Chart-Tire Noise/Vibration. Tire Noise/Vibration

2. Depends more on where the vehicle is operated
1. Bump/pothole, rough road or smooth road. GO to Symptom Chart-Suspension Noise/Vibration. Suspension Noise/Vibration
^ Noise is random or intermittent occurring from road irregularities. GO to Symptom Chart-Squeak and Rattle. Squeak and Rattle
^ Noise or vibration changes from one road surface to another. Normal sound changes.
^ Noise or vibration associated with a hard/firm ride. GO to Symptom Chart-Suspension Noise/Vibration. Suspension Noise/Vibration