User Manual

77
UT108/109 OPERATING MANUAL
UT108/109 OPERATING MANUAL
78
5. Mass Air Flow (MAF) Sensor (see gure 26)
The sensor converts the air ow into a DC voltage, low frequency or high frequency signal.
The Meter can only be used to test a DC voltage or low frequency signal.
Testing Procedure:
(1) Connect the DC voltage type MAF sensor in the DC voltage testing method and set the
rotary switch to DCV. Connect the frequency type MAF sensor in the RPM testing
method and set the meter to the number of cylinders in the automobile. Now take 4
cylinders (4CYL) for example.
(2) Connect the black test lead probe of the meter to the ground terminal (i.e. ground strap
connection) and connect the red one as illustrated in gure 25.
(3) Turn on the ignition key but do not start the engine.
Displayed Values:
DC Voltage Type Sensor: The displayed value should be less than or equal to 1V. (The
details shall be based on the parameters furnished by the supplier.)
Frequency Type Sensor: In a vacuum state, the displayed value should be 330 RPM±5%.
(This only applies to GM low frequency sensors.) The other low frequency sensors shall
be based on the parameters furnished by the supplier.)
Warning:
RPM =Frequency × 120/ the number of cylinders.