LG LSWS305ST Service Manual page 42

CHECKING FLOW CHART BY FAILURE MODE
Oven does not heat (including F-9 error)
No heating(including F-9 error)
Disconnect power
Check the electric wire connection
DLB and and harness of Relay and
each heater's connection.
And system PCB and Relay PCB(CN11)
Loose connection and disconnection
Is connection OK?
Yes
Check the thermostat open/short
between DLB Relay's L2 and L2 (BK wire)
If it have the error, it is open state.
Is it short?
1
No
No
Yes
Fix the connection
END
L2
Replace the thermostat.
5-10
L2
END