Symptom Charts
Noise, Vibration and Harshness (NVH) Symptoms
Classify Noise, Vibration and Harshness (NVH) Symptoms
For NVH concerns, it is necessary to classify the customer's concern into one of the 3 categories: noise, vibration or harshness. The reason for this is that a customer concern may consist of a combination of symptoms involving noise and vibration, or vibration and harshness. In cases where there are combination symptoms, determine which diagnostic path to follow: noise, vibration or harshness. For example, if a customer has a concern involving a noise and a vibration, and it is determined that it is vehicle speed-related, follow the vibration diagnostic path.
Noise Symptoms
Once a symptom is classified as a noise, the particular conditions under which the noise occurs need to be identified. These conditions are identified and verified during the road test. For example, a noise may only occur while turning. The next step is to determine which systems on the vehicle are related to that condition. In this case, the steering system and wheel/tire system may be suspect. After identifying possible systems, a preliminary inspection of these systems should be done. If the source of noise is still unidentified, use a listening device (such as the ChassisEAR) to pinpoint the source. Once the source has been identified, determine if this source is related to the suspected system previously identified. If it is related, then complete the repair to resolve the customer concern. If it is unrelated, then it is possible that the source of the noise is a reactor to a noise being transmitted through a transfer path. If this is the case, repairing the reactor will not resolve the customer concern. The transfer path must be identified and a determination made if the noise is normal, but accentuated by the transfer path (conductor), or if the originator is the fault causing excessive noise to transfer to another component through a conductor. There is a relationship between systems identified as related to conditions and the noise transfer path. In some cases, the condition under which the noise occurs has nothing to do with the identified source. This relationship is important in the diagnosis of noise concerns. It is the first clue that the identified source of noise might be a reactor and that further investigation is needed to diagnose a possible noise transfer path concern. Based on the results from the road test, make a determination of which action in the symptom chart to take first.
Vibration Symptoms
Most vibrations consist of movements back and forth or up and down that repeat. Every time the vibrating component goes through its complete range of motion and returns to the starting point is called a cycle. The rate at which these cycles occur within a given time is called the frequency. Frequency is measured in cycles per second or Hertz (Hz). One cycle per second equals one Hertz (Hz). Once the frequency of a vibration is known, calculations can be done to determine the system that is the source of the concern.
Order of Vibration
The order of a vibration refers to how often the vibration is present in one revolution of the component. For example, a vibration that is present once each revolution of a component would be a first order vibration. A vibration present twice each revolution of the component would be a second order vibration. Vibration orders do not have to be whole numbers, they can have decimal values such as 1.5 order vibration or 3.08 order vibration.
The concept of order of vibration is important to remember when the measured frequency of a vibration does not seem to match the frequency calculations of any of the likely systems or components. As the order increases, the frequency of the vibration will also increase by a multiple of that number.
For example, vibration may be present where the frequency is measured at 14 Hertz (Hz). After doing the necessary calculations it is determined the first order tire and wheel frequency is 7 Hertz (Hz) and the first order driveshaft frequency is 22 Hertz (Hz). Based on this information it can be determined the vibration is most likely a second order tire and wheel vibration: 7 Hertz (Hz) (first order tire and wheel frequency) multiplied by 2 (second order) equals 14 Hertz (Hz) (second order tire and wheel frequency).
Relationship of Vibration Frequency to Order of Vibration
After carrying out the road test as described in this Service Information, the vibration was determined to be either vehicle-speed related or electric motor-speed related. That determination will identify the vibration frequency calculations that should be done.
| Vibration Type | Calculate |
|---|---|
| Vehicle-speed related | Tire-speed vibration frequency, Driveshaft-speed vibration frequency |
In calculating and using frequency readings it is important to remember the direct relationship between Hertz (Hz) and Revolutions Per Minute (RPM). One Hertz (Hz) is equal to 60 Revolutions Per Minute (RPM). This is easy to remember. Think of Hertz (Hz) as cycles per second. There are 60 seconds in a minute, therefore multiply the Hertz (Hz) reading by 60 to get Revolutions Per Minute (RPM). Conversely, divide Revolutions Per Minute (RPM) by 60 to get Hertz (Hz).
Use the Frequency and Revolutions Per Minute (RPM) Calculations Worksheet to calculate system/component frequencies. The worksheet provides the necessary steps to determine each system/component group frequency.
Frequency Calculations
Calculating Tire and Wheel Frequency
For a vibration concern, use the vehicle speed to determine tire/wheel frequency and Revolutions Per Minute (RPM). Calculate the tire and wheel Revolutions Per Minute (RPM) and frequency by carrying out and following:
- Measure the diameter of the tire.
- Record the speed at which the vibration occurs.
- Obtain the corresponding tire and wheel Revolutions Per Minute (RPM) and frequency from the Tire Speed and Frequency Chart.
- If the vehicle speed is not listed, divide the vehicle speed at which the vibration occurs by 16 km/h (10 mph). Multiply that number by the 16 km/h (10 mph) tire Revolutions Per Minute (RPM) listed for that tire diameter in the chart. Then divide that number by 60. For example: a 40 MPH (Miles Per Hour) vibration with 835 mm (33 in) tires. 40 divided by 10 = 4. Multiply 4 by 105 = 420 Revolutions Per Minute (RPM). Divide 420 Revolutions Per Minute (RPM) by 60 seconds = 7 Hertz (Hz) at 40 MPH (Miles Per Hour).
Tire Speed and Frequency Chart
| Tire Diameter | Tire Revolutions Per Minute (RPM)/Hertz (Hz) at value listed below | Tire Revolutions Per Minute (Revolutions Per Minute (RPM)/Hertz (Hz) at value listed below | Tire Revolutions Per Minute (RPM)/Hertz (Hz) at value listed below | Tire Revolutions Per Minute (RPM)/Hertz (Hz) at value listed below |
|---|---|---|---|---|
| in (mm) | 9.9mph (16km/h) | 49.7mph (80km/h) | 60.3mph (97km/h) | 70.2mph (113km/h) |
| 19.02in (483mm) | 182 | 910/15 | 1092/18 | 1274/21 |
| 20.00in (508mm) | 173 | 865/14 | 1038/17 | 1211/20 |
| 20.98in (533mm) | 165 | 825/14 | 990/16 | 1155/19 |
| 22.05in (560mm) | 158 | 790/13 | 948/16 | 1106/18 |
| 23.03in (585mm) | 151 | 755/13 | 906/15 | 1057/18 |
| 24.02in (610mm) | 145 | 725/12 | 870/14 | 1015/17 |
| 25.00in (635mm) | 139 | 695/12 | 834/14 | 973/16 |
| 25.98in (660mm) | 134 | 670/11 | 804/13 | 938/16 |
| 26.97in (685mm) | 129 | 645/11 | 774/13 | 903/15 |
| 27.95in (710mm) | 124 | 620/10 | 744/12 | 868/14 |
| 28.94in (735mm) | 119 | 595/10 | 714/12 | 833/14 |
| 29.92in (760mm) | 115 | 575/10 | 690/11 | 805/13 |
| 30.91in (785mm) | 111 | 555/9 | 666/11 | 777/13 |
| 31.89in (810mm) | 108 | 540/9 | 648/11 | 756/13 |
| 32.87in (835mm) | 105 | 525/9 | 630/10 | 735/12 |
| 34.02in (864mm) | 102 | 510/8 | 612/10 | 714/12 |
Harshness Symptoms
Harshness is customer perception which gives the impression of no isolation from the tire/wheel and suspension system. Harshness may be caused by road conditions, temperature changes, component damage and/or incorrect customer modifications on original components/specifications. Customers usually experience harshness when the vehicle is driving over bumps or potholes and in cold weather conditions. Harshness can also be experienced with excessive tire pressure, sporty tires, heavy-duty springs and shocks, or other vehicle modifications. Some aftermarket tires, even with the correct size, may change vehicle behavior and produce customer concerns. The first step in diagnosing a harshness concern is to determine if the concern was experienced only in certain specific operating conditions, such as large potholes or extremely cold weather. In these cases, harshness should be considered normal. A known good vehicle can be driven under the same conditions and the rides can be compared to determine whether the concern is normal or vehicle specific. The second step is to check tire pressure and make sure it was set within vehicle specifications. The third step is to inspect for aftermarket or modified components and determine if they are the cause of the harshness complaint. If the harshness concern persists after the above steps, it is possible that some components are damaged. Based on the results from the road test, make a determination of which action in the symptom chart to take first.
Noise, Vibration and Harshness (NVH) Symptom Chart Categories
A good diagnostic process is a logical sequence of steps that lead to the identification of a causal system. Use the symptom and possible system categories as follows:
- Identify the operating condition that the vehicle is exhibiting.
- Match the operating condition to the symptom.
- Verify the symptom.
- Calculate the frequency and order of the symptom.
- Identify which category or system(s) could cause the symptom.
- The Service Information indicated to identify and diagnose the symptom or confirm that the system is not the source of the condition.
Use the diagnostic instructions in this Service Information along with the necessary listed tools to identify the vibration order and to isolate the symptom and the possible systems associated with that symptom. Then based on the results from the road test, make a determination of which action in the symptom chart to take first. Since it is possible any one of multiple systems may be the cause of the symptom, it may be necessary to use a process of elimination type diagnostic approach to pinpoint the concern.
Symptom Chart: Vehicle-Speed Related Vibrations
When a vehicle-speed related vibration is present, both tire-speed related vibration and axle shaft-speed related vibration calculations should be carried out.
Symptom Chart-Tire-Speed Related Vibrations
Symptom Chart
| Condition | Possible Sources | Actions |
|---|---|---|
| First order tire vibration | Tire or wheel | Symptom Chart: NVH REFER to: Wheels and Tires . |
| Wheel bearings | Symptom Chart: NVH REFER to: Front Suspension . | |
| Halfshaft | Symptom Chart: NVH REFER to: Front Drive Halfshafts . | |
| Brake rotor or drum | Symptom Chart: NVH REFER to: Brake System . | |
| Second order tire vibration | Tire or wheel | Symptom Chart: NVH REFER to: Wheels and Tires . |
| Third order tire vibration | Tire or wheel | Symptom Chart:NVH REFER to: Wheels and Tires . |
| Halfshaft | Symptom Chart: NVH REFER to: Front Drive Halfshafts . |
Symptom Chart-Driveshaft-Speed Related Vibrations
Symptom Chart
| Condition | Possible Sources | Actions |
|---|---|---|
| First order driveshaft vibration | Halfshaft | Symptom Chart: NVH REFER to: Front Drive Halfshafts . |
| Second order driveshaft vibration | CV-joint | Symptom Chart: NVH REFER to: Front Drive Halfshafts . |
| Third order driveshaft vibration | Drive axle | Symptom Chart: NVH REFER to: Front Drive Halfshafts . |
Symptom Chart: Powertrain-Speed Related Vibrations
Symptom Chart
| Condition | Possible Sources | Actions |
|---|---|---|
| First through sixth order powertrain vibration | Transmission/transaxle | Symptom Chart: NVH REFER to: Diagnosis By Symptom . |
| Transmission/transaxle mounts | Symptom Chart: NVH REFER to: Diagnosis By Symptom . | |
| Accessory speed related vibration | Coolant pump(s) | Symptom Chart: NVH REFER to: Engine . |
| A/C compressor motor | Symptom Chart: NVH REFER to: Climate Control System - Vehicles With: Dual Automatic Temperature Control (DATC) or REFER to: Climate Control System - Vehicles With: Electronic Manual Temperature Control (EMTC) . |
Symptom Chart: Engine-Speed Related Vibrations
Symptom Chart
| Condition | Possible Sources | Actions |
|---|---|---|
| 0.5 order engine vibration | Engine | Symptom Chart: NVH REFER to: Engine . |
| Engine | Symptom Chart: NVH REFER to: Engine . | |
| First through sixth order engine vibration | Engine | Symptom Chart: NVH REFER to: Engine . |
| Engine mounts | REFER to: Engine . | |
| Transmission/transaxle | Symptom Chart: NVH REFER to: External Controls . | |
| Exhaust system | Symptom Chart: NVH REFER to: Exhaust System . | |
| Belt driven accessory drive vibration | Engine pulley | Symptom Chart: NVH REFER to: Engine . |
| Accessory drive belt | Symptom Chart: NVH REFER to: Accessory Drive . | |
| Coolant pump | Symptom Chart: NVH REFER to: Engine Cooling . | |
| Generator | Symptom Chart: NVH REFER to: Charging System - 2.5L Duratec (125kW/170PS) . | |
| A/C compressor | Symptom Chart: NVH REFER to: Climate Control System - Vehicles With: Dual Automatic Temperature Control (DATC) or REFER to: Climate Control System - Vehicles With: Electronic Manual Temperature Control (EMTC) . |
Symptom Chart: Noise, Air Leaks or Water Leaks
Symptom Chart
| Condition | Possible Sources | Actions |
|---|---|---|
| Wind noise, air or water leaks | Body | Symptom Chart: Body System - General Information Refer to Body Panel System - Body Repairs - General Information |
| Front end noise while driving vehicle | Front suspension | Symptom Chart: NVH REFER to: Front Suspension . |
| Drive axle | Symptom Chart: NVH REFER to: Front Drive Halfshafts . | |
| Brake system | Symptom Chart: NVH REFER to: Brake System . | |
| Steering linkage or gear | Symptom Chart: NVH REFER to: Power Steering . | |
| Transmission/transaxle | Symptom Chart: NVH REFER to: External Controls . | |
| Body | Symptom Chart: Body System - General Information Refer to Body Panel System - Body Repairs - General Information | |
| Rear end noise while driving vehicle | Rear suspension | Symptom Chart: NVH REFER to: Rear Suspension . |
| Drive axle | Symptom Chart: NVH REFER to: Front Drive Halfshafts . | |
| Brake system | Symptom Chart: NVH REFER to: Brake System . | |
| Transmission/transaxle | Symptom Chart: NVH REFER to: Diagnosis By Symptom . | |
| Body | Symptom Chart: Body System - General Information Refer to Body Panel System - Body Repairs - General Information | |
| Noise with vehicle stopped | Transmission/transaxle | Symptom Chart: NVH REFER to: External Controls . |
| A/C compressor motor | Symptom Chart: NVH REFER to: Climate Control System - Vehicles With: Dual Automatic Temperature Control (DATC) or REFER to: Climate Control System - Vehicles With: Electronic Manual Temperature Control (EMTC) . | |
| Body | Symptom Chart: Body System - General Information Refer to Body Panel System - Body Repairs - General Information |
Symptom Chart: Harshness
Symptom Chart
| Condition | Possible Sources | Actions |
|---|---|---|
| Harsh vehicle ride | Front suspension | Symptom Chart: NVH REFER to: Front Suspension . |
| Rear suspension | Symptom Chart: NVH REFER to: Rear Suspension . |