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Connect:
•
Jumper wires between the fuel injector and the harness connector.
•
Black test probe to a good ground near the fuel injector or the negative (-) vehicle battery post.
•
Red test probe to the fuel injector solenoid driver input on the jumper cable.
Start the engine. Pulse width is shown in milliseconds.
If reading is too high (overrange) or unstable, adjust the trigger level by pressing the "±TRIG" button repeatedly.
Frequency (Automotive Hz) Measurements
Frequency is the number of cycles a signal completes each second. There are many sensors and signals on
a vehicle that produce a frequency that can be measured. For example, wheel speed sensors, vehicle speed
sensors, fuel injector control signals, cam and crank outputs, and engine reference signals. This example
measures the frequency output of a digital mass air flow sensor (MAF). Output can vary from several hundred
Hz to ten thousand Hz depending on the type of MAF sensor.
NOTE:
Although similar in appearance, MAF sensors made by different manufacturers function differently,
have different frequency ranges and squarewaves, and are not interchangeable. Voltage level of
squarewaves should be consistent. Frequency should change smoothly with engine load and speed.
Meter setup to measure frequency:
•
Set the rotary switch to the RPM IG (RPM IG) setting.
•
Press the "%DUTY" button until "Hz" appears on the display.
•
Insert the black lead in the "COM" jack.
•
Insert the red lead in the "
800.MACTOOLS
All manuals and user guides at all-guides.com
Black lead
to the MAF
signal ground
Black
Jumper leads
from MAF
sensor
Red
" jack.
RPM IG
Red lead to
the MAF
signal output
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