LG LMV1640DW Service Manual page 30

(2) CHECKOUT PROCEDURES FOR RELAY.
- PROBLEM (A) -
T.T. motor and oven lamp turn on without touching
START key when the door is closed.
NO
Remove the mate connector of I/O
GOOD
CON from the circuit board.
Does the unit still operate?
Replace the
circuit board
YES
NO YES
Defective
RELAY3
Replace
RELAY3
7-19
- PROBLEM (B) -
T.T. motor and oven lamp turn on When the door is
closed and START key is touched.
YES
Measure the voltage at pin NO.
GOOD
4 of U01
Voltage reading: 0 Vdc
NO
Replace the
circuit board
NO
YES
Defective
RELAY3 or poor
connection of
RELAY3
Replace
RELAY3 or correct
the connection.