GMC chevrolet camaro 2000 Service Manual page 93

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Vibration Diagnosis and Correction
EVA Sensor Placement
Proper EVA sensor placement is critical in order to
take proper vibration readings. You can place
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the sensor anywhere on the vehicle where vibrations
are felt (1 ). Use putty or a hook and loop fastener
in order to hold the sensor in place on non-ferrous
surfaces, such as the surface of the steering column.
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A magnet holds the sensor to ferrous surfaces.
Vibrations are typically felt in an up-and-down
direction. The sensor is directionally sensitive.
Therefore, place the sensor as flat as possible with
the side marked UP facing upward. Place the UP side
of the sensor in the exact position every time for
consistent results when repeating the tests or making
a comparison.
General Information
EVA Display
Up to three dominant vibration frequencies are (
displayed on the EVA's liquid crystal screen. On the
left is the frequency reading, followed by a description
of the vibration source. At the right side of the
screen, the actual strength, or amplitude, is shown in
acceleration force (G's).
Frequencies can be displayed in revolutions per
minute (RPM) or in Hertz (Hz). Switch between the
two readings by pressing the RPM/Hz button on
the keypad.
Important: Verify that the letter on the display
matches the correct sensor input.
EJBOOOOB
~DDDB
l\alDDDl~~~1
!\vG
l
D
jeNTERl
J
EXIT
j
J,AE•z•!
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Next to the frequency data on the top line of the
screen is the letter A or B. This letter indicates which
input is activated. Press the NB button on the
keypad in order to switch between the two inputs and
set to the correct input that is being used.
The EVA offers the following main display features, all
of which are described below:
• Freeze
• Record/Playback
• Averaging/Non-Averaging Modes
" Strobe Balancing
• Smart Strobe
• Auto Mode
Freeze
Pressing the FREEZE button on the keypad activates
the freeze function, which locks the display of data.
The display changes to Hz_FR_ V
==
XX G
and a caret symbol points to a vibration source.
Additional diagnostic information or that vibration
source can be viewed by pressing ENTER. The freeze
function is useful when conducting an
acceleration/deceleration test in which the significant
amount of vibration registers only for a very short t'1me.
Pressing EXIT or the FREEZE button again
deactivates the freeze function.
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