LG LMV1925SW Service Manual page 30

(2) CHECKOUT PROCEDURES FOR RELAY.
FAN motor and oven lamp turn on without touching
START key when the door is closed.
NO
GOOD
- PROBLEM (A) -
YES
Remove the mate connector of I/O
CON from the circuit board.
Does the unit still operate?
NO
Replace the
circuit board
YES
Defective
RELAY1
Replace
RELAY1
FAN motor and oven lamp turn on When the door is
closed and START key is touched.
YES
GOOD
Replace the
circuit board
7-19
- PROBLEM (B) -
NO
Measure the voltage at pin NO.
35 of U01
Voltage reading: 0 Vdc
10 of U03
Voltage reading: about 15V
NO
Defective
RELAY1 or poor
connection of
RELAY1 or correct
the connection.
YES
RELAY1
Replace