3
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- Block the front wheels.
- Apply BOTH the service brakes and the park brake.
- With the scan tool and the
J-38792-A Electronic Vibration Analyzer (EVA) 2
, if available, still installed, start the engine.
- Place the transmission in NEUTRAL or PARK.
- Slowly increase the engine RPM to the level at which the disturbance is most noticeable.
- Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the
J-38792-A Electronic Vibration Analyzer (EVA) 2
, if available.
- Place the transmission in DRIVE.
- Slowly increase the engine RPM to the level at which the disturbance is most noticeable.
- Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the
J-38792-A Electronic Vibration Analyzer (EVA) 2
, if available.
- If no frequency data was obtained, or if the
J-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?
| Go to
Step 4
| Go to
Vibration Diagnostic Aids
|
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. Refer to
Vehicle-to-Vehicle Diagnostic Comparison.
- Install a scan tool into the known good vehicle.
- Install the
J-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.
- Block the front wheels.
- Apply BOTH the service brakes and the park brake.
- Start the engine.
- Place the transmission in NEUTRAL or PARK.
- Slowly increase the engine RPM to the level at which the disturbance was most noticeable in the customer's vehicle.
- Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the
J-38792-A Electronic Vibration Analyzer (EVA) 2
, if available.
- Place the transmission in DRIVE.
- Slowly increase the engine RPM to the level at which the disturbance was most noticeable in the customer's vehicle.
- Record the engine RPM obtained on the scan tool and the most dominant frequency reading if obtained on the
J-38792-A Electronic Vibration Analyzer (EVA) 2
, if available.
- If no frequency data was obtained, or if the
J-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?
| Go to
Vibration Diagnostic Aids
| Go to
Vibration Analysis - Engine/Accessory Isolation
|