WM2701HV - LG Washing Machine Service Manual (repair manual). Page 39

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.