E N G L I S H
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and signals on a vehicle that have a
frequency that can be measured. Wheel
Speed sensors, Vehicle Speed sensors, Fuel
Injector control signals, Cam and Crank
outputs and engine reference signals are
examples.
This example measures the frequency
output of a digital Mass Air Flow sensor.
Depending on the type of MAF sensor, the
output can be from several hundred to ten
thousand Hz.
NOTE: Although similar in appearance,
MAF sensors made by different
manufacturer function differently, have
different frequency range’s square waves
and are not Interchangeable. Voltage
level of square waves should be consistent.
Frequency should change smoothly with
engine load and speed.
RED LEAD
TO THE MAF
SIGNAL OUTPUT
BLACK LEAD
TO THE MAF
SIGNAL GROUND
JUMPER
LEADS
FROM MAF
SENSOR
RED (+)
BLACK (-)
To measure duty cycle (%):
• Select the mS-Pulse range with the rotary
switch.
• Press the HOLD (Hz) button until Hz
appears on the right side of the display.
Insert:
• Black lead in COM jack.
• Red lead in RPM, V, Ω jack.
Connect:
• Jumper wires between the MAF sensor
and the hamess connector.
• Black test probe to the ground jumper
wire.
• Red test probe to the signal output
jumpers wire.
Start the engine. At idle, note the
frequency displayed on the Meter. Move
the throttle and note the change in
frequency displayed.
If reading is unstable, adjust the trigger
lever pressing the ±TRIG button repeatty.
Frequency (Non-Automotive)
Measurements.
The meter has two frequency
measurement modes: the nonautomotive
Hz measurement
(approximate trigger level: 3000 mV) mode
for the general frecuency counter mode
and the automotive Hz measurement.
In the nonautomotive Hz measurement
mode,
the meter autoranges to one of four
ranges: 199.99 Hz, 1999.9 Hz, 19.999 KHz
and 199.99 KHz.
If the input signal is below the trigger level,
frequency measurement will not be taken.
If your readings are unstable, the input
signal may be near the trigger level for
that range. You can usally correct this by
selecting a lower range using the RANGE
button. If your readings seem to be a
multiple of what you expected, your input
signal may have distortion or ringing
like the signals from electronic motor
controls. In this case, use the automotive
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