Diagnosing Vibration Concern (IB05-14-S001)

Electronic Vibration Analyzer

Fig 1: Identifying Electronic Vibration Analyzer

If a customer complains of vibration, it is important to have the proper resources for diagnosis. The 12-volt J 38792-A Electronic Vibration Analyzer (EVA) is a technological diagnostic tool used to aid in diagnosis of the vibration. Over the years the J 38792-A Electronic Vibration Analyzer (EVA) has evolved to become more sophisticated and aids in finding areas of vibration concern.

The 12-volt J 38792-A Electronic Vibration Analyzer (EVA) receives input from an attached vibration sensor or accelerometer and displays the most dominate input frequency/frequencies (up to three) on its liquid crystal display. The vibration concern frequency/frequencies are obtained through the use of the J 38792-A while following the Vibration Analysis Diagnostic Tables. The frequency/frequencies obtained with the Vibration Analysis Diagnostic Tables are used as a primary input to help determine the source of the vibration concern.

EVA Vibration Sensor

The J 38792-A vibration sensor incorporates a 6.1 m (20 ft) cord, which allows the sensor to be placed on virtually any component of the vehicle where vibration is felt.

The J 38792-A contains two sensor input ports which can be activated individually to allow for two individual vibration sensor inputs. The vibration sensors can then be placed in two different locations in the vehicle and their individual inputs can be read without having to stop a test, move the sensor and resume the test. The use of two vibration sensors can help find and record an accurate frequency of the vibration concern, and in making comparisons between two different areas of a single component, or a vehicle system, during the diagnostic process.

The following worksheet is to be used in conjunction with the appropriate Vibration Analysis-Road testing procedure listed in the Service Manual. Fill out the applicable portion of the worksheet that applies to the vibration/noise.

Refer to the appropriate section of the Service Manual for specifications and repair procedures related to the vibration concern.

Vibration Analysis Worksheet

Fig 2: Vibration Analysis Worksheet (1 Of 5)

Fig 3: Vibration Analysis Worksheet (2 Of 5)

Fig 4: Vibration Analysis Worksheet (3 Of 5)

Fig 5: Vibration Analysis Worksheet (4 Of 5)

Fig 6: Vibration Analysis Worksheet (5 Of 5)