Test 4 Moisture Sensor - LG DGS2028EKD Service Manual

Test 4
Test 4
Moisture sensor
Moisture sensor
NOTE: This test has two parts. The best test of the moisture sensing system is done in the diagnostic mode. This
FUNCTIONAL TEST will test the sensor bars, wiring harness and PCB operation. If the results of this test are normal,
the sensor system and PCB response are normal. The problem is somewhere else.
FUNCTIONAL TEST (Control)
1. Enter the diagnostic mode. (See DIAGNOSTIC TEST MODE on page 18.)
2. With the door closed, press the START/PAUSE button once. The dryer will start tumbling without heat.
3. Open the door. The drum will stop tumbling and the "dE" error code will be displayed and the chime will sound several times (if turned on).
4. With one hand, reach into the drum and place your fingers across the moisture sensor bars.
(CAUTION: The dryer drum will turn in this test. Your hand will be close to the rotating drum vanes. Keep your hand close to the filter housing to
avoid being hit by the moving vanes.)
5. Use your other hand to press the door switch. The dryer drum will start rotating automatically.
6. Observe the numerical display. Depending on conditions, the number displayed should be between 30 and 255. The numbers should start
decreasing as the control senses the moisture in your skin.
7. After you have observed the number decreasing, remove your fingers from the sensor bars. The numbers will continue to decrease for a few
seconds (minimum 30) and the begin to increase (maximum 239).
8. If this test fails, proceed with the MECHANICAL TEST below.
MECHANICAL TEST
Disconnect the NA6
connector from the main
PCB. Measure the resistance
between the NA6-6 (GN) pin
and a chassis ground screw.
Is the resistance <1 Ω ?
Put a jumper between NA6-
2 (OR) and NA6-4 (BL) to
create a circuit connection
for the continuity test in the
next step.
Measure the resistance
between the two moisture
sensor bars on the in the lint
filter housing inside the drum.
Is the resistance <1 Ω?
Check all connections and
wires between the NA6
terminal at the main PCB and
the sensor bars. Check the
resistance is 0Ω.
• Measure the resistance of all wires.
Resistance should be < 1 Ω.
• Check all sensor harness connectors
for corrosion, loose/bent pins, broken
wires, etc.
• Check all harness wires between the
main PCB and the sensor for cuts, or
broken wires.
• Check all
wiring
harness
NO
connections,
wires and
ground
screws.
YES
YES
• Replace the
main PCB.
YES
NO
YES
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