Vibration Diagnosis and Correction | Diagnostic Information and Procedures | Document ID: 5046923
Vibration Analysis - Road Testing (CH-51450-NVH
Oscilloscope)
Special Tools
CH-51450-NVH Oscilloscope Diagnostic Kit (w/NVH)
EL-47955 Multi Diagnostic Interface (MDI)
For equivalent regional tools. Special Tools and Equipment
Test Description
The numbers below refer to the step numbers on the diagnostic table.
- Proper location of the CH-51450-NVH oscilloscope accelerometer onto the component which
is most excited by the vibration disturbance is critical to obtaining an accurate frequency
reading.
This test will duplicate virtually any disturbance which occurs while the vehicle is in motion.
- Accelerate to a speed high enough above the speed of the disturbance to allow for the time
needed to shift into NEUTRAL and for the engine to decrease in RPM to idle speed before
coasting down through the disturbance range.
- This test will either eliminate or confirm the engine as a contributing cause of the customer
concern.
Vibration Analysis - Road Testing
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Step |
Action |
Yes |
No |
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Warning: Road Test Warning. |
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1 |
Did you review the Diagnostic Starting Point – Vibration Diagnosis? |
Go to Step 2 |
Go to Vibration Diagnosis, Starting Point, and Correction |
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2 |
Did the customer concern indicate that the vibration occurs ALSO while the vehicle is idling at a stop? |
Go to Vibration Analysis - Engine |
Go to Step 3 |
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3 |
Visually inspect the tire and wheel assemblies, steering components and suspension components for any possible faults. Are the tire and wheel assemblies, steering components and suspension components in good working condition? |
Go to Step 5 |
Go to Step 4 |
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4 |
Note: Do NOT operate the vehicle until the faults are corrected. |
Go to Step 5 |
Go to Step 3 |
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Step |
Action |
Yes |
No |
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Correct the faults with the tire and wheel assemblies, steering components, and/or the suspension components before proceeding. Did you correct the faults with the tire and wheel assemblies, steering components, and/or the suspension components? |
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5 |
Obtain the drive axle final drive ratio. Did you obtain the drive axle final drive ratio? |
Go to Step 6 |
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6 |
Install the CH-51450-NVH Oscilloscope and the EL-47955 MDI. Is the CH-51450-NVH Oscilloscope operating properly? |
Go to Step 7 |
Go to Oscilloscope Diagnostic Kit Description and Operation |
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7 |
Did the customer concern indicate that the vibration occurs ONLY during heavy acceleration at launch? |
Go to Step 8 |
Go to Step 11 |
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8 |
1. Install the CH-51450-NVH-TA183 accelerometer to the pinion area of the drive axle. Route the accelerometer cable clear of rotating parts and loosely secure the wire clear of moving parts. If it is not possible to install the CH-51450-NVH-TA183 accelerometer to the drive axle, install the accelerometer to an exposed portion of the floor panel or seat track in the area that the customer noted is most respondent to the vibration. 2. Select a smooth, level road. 3. With the vehicle at a stand-still, apply the brake pedal and place the transmission in the lowest forward gear. Note: Do not accelerate to the point of causing the drive wheels to squeal, slip, or hop. This would obscure the results of the test. 4. Release the brake pedal and accelerate aggressively to 32 km/h (20 mph). 5. Observe the vehicle for disturbances that match the customers description and note the following conditions: The vibration frequency reading, if detected, by the CH-51450-NVH Oscilloscope The feel and/or sound of the disturbance 6. If a reading could not be obtained by the CH- 51450-NVH Oscilloscope, move the CH- |
Go to Step 9 |
Go to Step 11 |
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| Step |
Action |
Yes |
No |
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51450-NVH-TA183 accelerometer to another part that is respondent to the vibration and repeat Steps 3–5. Were you able to duplicate the customer concern? |
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| 9 |
Is the vehicle primary driveline configuration rear wheel drive? |
Go to Step 10 |
Go to Step 11 |
| 10 |
Is the vehicle equipped with a solid drive axle? |
Go to Vibration Analysis - Driveline |
Go to Vibration Analysis - Hub and/or Axle Input |
| 11 |
1. Install the CH-51450-NVH-TA183 accelerometer to the component identified by the customer as most respondent to the vibration. If no component was identified, install the CH-51450-NVH-TA183 accelerometer to the drivers side right seat rail. You may have to move the sensor to other locations later. 2. Select a smooth, level road and slowly accelerate the vehicle up to highway speed. 3. Observe the vehicle for disturbances that match the customers description and note the following conditions or take a snapshot using the CH-51450-NVH software: The vehicle speed The engine RPM The transmission gear range and the specific gear The vibration frequency reading, if detected, by the CH-51450-NVH Oscilloscope The feel and/or the sound of the disturbance 4. If the vibration seems to excite a particular component of the vehicle more than the sear rail, move the CH-51450-NVH-TA183 accelerometer onto that component and repeat Steps 2 and 3. Were you able to duplicate the customer concern? |
Go to Step 14 |
Go to Step 12 |
| 12 |
Is the vehicle equipped with selectable four wheel drive? |
Go to Step 13 |
Go to Step 14 |
| Step |
Action |
Yes |
No |
| 13 |
1. With the CH-51450-NVH-TA183 accelerometer still installed in the same position, activate/engage four wheel drive. 2. Select a smooth, level road and slowly accelerate the vehicle up to highway speed. 3. Observe the vehicle for disturbances that match the customers description and note the following conditions or take a snapshot using the CH-51450-NVH software. The vehicle speed The engine RPM The transmission gear range and the specific gear The vibration frequency reading, if detected, by the CH-51450-NVH Oscilloscope The feel and/or sound of the disturbance 4. If the vibration seems to excite a particular component of the vehicle more than the seat rail, then move the CH-51450-NVH-TA183 accelerometer onto that component and repeat Step 2 and 3. Were you able to duplicate the customer concern? |
Go to Step 14 |
Go to Vibration Diagnostic Aids |
| 14 |
1. Accelerate the vehicle to a speed higher than the speed at which the disturbance occurs. 2. Shift the vehicle into NEUTRAL and allow the vehicle to coast down through the disturbance range. Does the disturbance still occur while coasting down in NEUTRAL? |
Go to Step 16 |
Go to Step 15 |
| 15 |
1. Select a smooth, level road and slowly accelerate the vehicle up to the speed at which the disturbance occurs. 2. Decelerate and safely downshift by one gear range. 3. Operate the vehicle at the same VEHICLE SPEED at which the disturbance occurs. Does the same disturbance still occur while going the same vehicle speed in a lower gear range? |
Go to Vibration Analysis - Hub and/or Axle Input |
Go to Vibration Analysis - Engine |
| Step |
Action |
Yes |
No |
| 16 |
If the CH-51450-NVH Oscilloscope is not available, refer to Symptoms - Vibration Diagnosis and Correction. Did the CH-51450-NVH Oscilloscope detect a dominant frequency? |
Go to Step 17 |
Go to Symptoms - Vibration Diagnosis and Correction |
| 17 |
Does the frequency data clearly fall within the tire/wheel parameters ONLY? |
Go to Vibration Analysis - Tire and Wheel |
Go to Step 18 |
| 18 |
Does the frequency data clearly fall within the propeller shaft parameters ONLY? |
Go to Vibration Analysis - Driveline |
Go to Symptoms - Vibration Diagnosis and Correction |