F1281ND5, F1281HD5 - LG Washing Machine Service Manual (repair manual). Page 36

9-2. DOOR LOCK SWITCH ASSEMBLY

AC
Common
terminal
of Valve

The Door Lock Switch Assembly consists of a Heating PTC, a Bimetal,
a Protection PTC, and a Solenoid. It locks the door during a wash cycle.

1. Operation for door closing

- After the system turns on, PTC heating starts up through terminal 2~4 s

authorizing the power on.

- After PTC heating starts up and before solenoid operation is driven,

force the system to the off position through CAM.

Door close

- Authorizing one impulse through terminal 3~4 (PTC & solenoid) will

make the door locked.

- Door lock is detected when switches in terminal 4~5 are set closed.

CAM rotation will forcibly clear off the connection.
The maximum, allowable number of impulse authorizations is 2.
Upon the third authorization of the impulse, the position of CAM goes
back to the door-open position.

- Authorizing the impulse occurs in 4.5 seconds upon input for max

performance and two authorization processes are allowed at most.

Normal operation period of PTC heating: 1.5 — 5 seconds.
(Defects from the development process.)

2. Operation for door opening

- With a temporary stop, door automatically opens by CAM rotations after

authorizing the impulse from the terminal 3 ~ 4 and the power turns 
off — maximum of 3 times of the authorizing period.

- Upon the fourth authorization of the impulse, the position of CAM goes

back to the door-close position.