LG WM3677HW Owner's Manual page 111

Repair – Water Level Switch
The water level detector switch monitors the water level and feeds this
information to the MICOM. The sensor reads air pressure in an air
chamber on the tub. The air pressure changes in relation to the depth
of the water, moving a diaphragm in the switch. As the water level
fluctuates, it raises or lowers the coil, which, in turn, changes the
electric resonance of the oscillator circuit of which it is a part. As water
level decreases, frequency increases. (e.g. A low water level may read
25.5kHz, while a high water level may read 21.4 kHz. These readings are
approximate; washers in the field may vary slightly from these figures.)
To read the frequency while the COMBO is running, press and hold the
SPIN SPEED and SOIL LEVEL buttons. The number on the display
should be divided by 10 to obtain the frequency reading in kHz. A
display of 254 would indicate a frequency of 25.4 kHz. The MICOM
interprets the frequency reading as one of eight levels, with one being
the lowest water level and any level greater than eight indicating an
overflow situation.
WM3677HW p50