Vibration Diagnosis and Correction | Diagnostic Information and Procedures | Document ID: 5040251
Special Tools
CH-51450-NVH Oscilloscope Diagnostic Kit (w/NVH)
EL-38792-A Electronic Vibration Analyzer (EVA)
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.
2. If powertrain related DTCs are present, there may be a powertrain performance condition
present which could be a contributing cause to the customer’s concern.
5. Making comparisons of the customer’s vehicle with an equally equipped, same model year
and type, KNOWN GOOD vehicle will help determine if certain disturbances may be
characteristic of a vehicle design.
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Step |
Action |
Yes |
No |
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Warning: Work Stall Test Warning |
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1 |
Can vibration be felt at engine idle when parked? |
Go to Step 2 |
Go to Vibration Analysis - Road Testing |
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2 |
Using a scan tool, determine if any DTCs are set. Were any DTCs set? |
Go to Diagnostic Starting Point - Vehicle |
Go to Step 3 |
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3 |
1. Block the front wheels. 2. Apply BOTH the service brakes and the park brake. 3. With the CH-51450-NVH Oscilloscope Diagnostic Kit (w/NVH) and the EL-47955 Multi Diagnostic Interface (MDI), or the scan tool and the EL-38792-A Electronic Vibration Analyzer (EVA) 2, if available, still installed, start the engine. 4. Place the transmission in NEUTRAL or PARK. 5. Slowly increase the engine RPM to the level at which the disturbance is most noticeable. 6. Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the CH-51450-NVH Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A Electronic Vibration Analyzer (EVA) 2, if |
Go to Step 4 |
Go to Vibration Diagnostic Aids |
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Step |
Action |
Yes |
No |
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7. Place the transmission in DRIVE. 8. Slowly increase the engine RPM to the level at which the disturbance is most noticeable. 9. Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the CH-51450-NVH Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A Electronic Vibration Analyzer (EVA) 2, if available. 10. If no frequency data was obtained, or if the CH-51450-NVH Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A Electronic Vibration Analyzer (EVA) 2, is not available, place the transmission into REVERSE, then repeat steps 8 and 9. Reverse-loading of the powertrain may increase or change the characteristics of the vibration. Were you able to duplicate the customer’s concern? |
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4 |
Did the CH-51450-NVH Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A Electronic Vibration Analyzer (EVA) 2 detect a dominant frequency, or was a significant vibration present? |
Go to Vibration Analysis - Engine/Accessory Isolation |
Go to Step 5 |
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5 |
Compare the test results of the customer’s vehicle to the results of the same tests run, at the same engine RPM, on an equally-equipped, same model year and type, KNOWN GOOD vehicle. Vehicle-to- Vehicle Diagnostic Comparison 1. Install a scan tool into the known good vehicle. 2. Install the CH-51450-NVH Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A Electronic Vibration Analyzer (EVA) 2, if available, into the known good vehicle; place the sensor in exactly the same location as it was placed in the customer’s vehicle. 3. Block the front wheels. 4. Apply BOTH the service brakes and the park brake. 5. Start the engine. 6. Place the transmission in NEUTRAL or PARK. 7. Slowly increase the engine RPM to the level at which the disturbance was most noticeable in the customer’s vehicle. 8. Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the CH-51450-NVH Oscilloscope |
Go to Vibration Diagnostic Aids |
Go to Vibration Analysis - Engine/Accessory Isolation |
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Action |
Yes |
No |
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Electronic Vibration Analyzer (EVA) 2, if available. 9. Place the transmission in DRIVE. 10. Slowly increase the engine RPM to the level at which the disturbance was most noticeable in the customer’s vehicle. 11. Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the CH-51450-NVH Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A Electronic Vibration Analyzer (EVA) 2, if available. 12. If no frequency data was obtained, or if the CH-51450-NVH Oscilloscope Diagnostic Kit (w/NVH) or the EL-38792-A Electronic Vibration Analyzer (EVA) 2, is not available, place the transmission into REVERSE, then repeat steps 10 and 11. Reverse-loading of the powertrain may increase or change the characteristics of the vibration. Did both of the vehicles exhibit the same characteristics? |
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