7-56 2002 Buell S3T: Electrical
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TACHOMETER PERFORMANCE CHECK 7.14
GENERAL
See Figure 7-64. Use the SPEEDOMETER TESTER (Part
No. HD-41354) for tachometer diagnostics. These diagnos-
tics may include:
● Checking tachometer operation.
● Testing tachometer needle sweeping action.
The tester can be connected to the vehicle’s cam position
sensor connector. This connection introduces a signal to the
ignition module that simulates the signal from the cam posi-
tion sensor. The ignition module will use this simulated signal
to open and close circuits to fire the spark plugs. This allows
you to simulate the engine running and therefore generate
tachometer readings.
TESTING
Operation Test
1. See Figure 7-71. Connect the speedometer tester to the
cam position sensor Deutsch socket housing.
2. Convert the desired test RPM to a tester frequency in
Hertz. Several conversions are listed in the table below
a. Select a desired tachometer reading for testing. This
example will use 2000 RPM.
b. Divide the desired tachometer reading by 60. For
example, 2000/60=33.3.
3. Enter the result (33.3 for 2000 RPM) into the speedome-
ter tester.
a. The tachometer should respond by moving its nee-
dle to the desired RPM.
b. Test the tachometer at several different RPM read-
ings to verify proper operation.
NOTE
All tachometer accuracy tolerances were taken at 68°-77° F
(20-25° C).
Sweep Test
1. See Figure 7-71. Connect the speedometer tester to the
cam position sensor Deutsch socket housing.
2. Place speedometer tester power switch in the ON posi-
tion. Place signal switch in the OUT position.
3. Turn vehicle ignition switch ON.
4. Begin test by pressing 0 on the tester keypad, then
pressing ENTER. The tester will scan for two seconds,
then the tester will put out a 1 Hz signal.
5. Select a test range.
a. Press 2 to select LO range.
b. Press 5 to select CEN range.
c. Press 8 to select HI range.
6. After selecting a range, use the corresponding arrow
keys to accelerate through the range. As you move
through the speed range, check for smooth needle
movement.
a. If testing LO range, press 1 or 3.
b. If testing CEN range, press 4 or 6.
c. If testing HI range, press 7 or 9.
Table 7-8. Tachometer Accuracy
Tolerances
READING
2000
RPM
4000
RPM
6000
RPM
7500
RPM
Tol erance
(+/- RPM)
100 120 210 320
Conversion
factor
33.3 66.7 100 125
Figure 7-71. Testing Tachometer
/WGN
/WBK
R/W
ABC
ABC
ABC
b0592x7x
2
3
4
1. Deutsch Socket Housing Test Connector
2. Deutsch Socket Housing
3. Deutsch Pin Housing
4. Cam Position Sensor
1
Wires continue to
Ignition Module
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