How a washing machine door lock or interlock works
How can you tell if a door interlock is faulty?
Washing machine door locks really only get 3 major faults
- The points between live and common fail in some way.
- The NTC heater or bi-metal strip fail.
- The plastic gets to hot and distorts inside the lock causing it to jam.
Understanding how a door interlock works helps you decide if it is faulty or not.
Washing machines must have some way in which you can lock the door closing mechanism when the machine is started up and then unlock them with a certain delay (normally two minutes) after the current has switched off via the program or on/off switch, in order to ensure that the door cannot be opened while some of the components are still rotating initially (in particular the motor and the drum of the spin-dryer).
When you shut the door, the latch on the door pushes inside the door lock onto a sliding bar which moves over and activates an electrical part inside which locks the door shut. At the same time, power is passed through the interlock on to the rest of the machine. The actual latching shut of the door is a simple spring-loaded mechanism where the latch just slips into the door catch and the door stays closed. Locking the door is a separate process.
The locking of the door.
locking pin on a washing machine door lock or interlock
Washing machines have a bi-metal strip inside the door lock which is heated by PTC Heater (resister) when live and neutral are activated on to the pcts it heats up and bends the bi-metal strip which then moves the arm to activate the common terminal and push a pin into the closed door to lock it in place. Once this has happened (usually a second or so see video) the power then can flow through to the common wire, and therefore on to the rest of the machine allowing it to start.
The only test you can do without a test rig is to check the PTC Heater on the live and neutral you might expect to get a resistance reading of something like 1000 Ohm but this can vary depending on manufacture of the interlock and the condition of the PTC,
burnt part of bi-metal strip
The parts of a lock
the common and live contact
56 Responses to “How a washing machine door lock or interlock works”
Many thanks for your useful videos on youtube. I had a look at your instructions for replacing the door interlock on a Bosch Washing machine but the interlock on my Bosch Classixx 1200 Express WF02467GB is not held in place by screws but what seem to be white plastic Dowls? Can you tell me how to remove this interlock? Many Thanks. Tim
Hi Tim, just press gently but firmly on one of those plastic buttons and at the same time firmly pull the unit (behind) towards the rotational center of the drum (in the leftwards direction if looking at front of machine).
The unit will pop out and you can manoeuvre it out from there.
Hi! Thanks for this videos on youtube. Is verry useful. I have a problem with an LG washing machines (F1256LD ). The door interlock is faulty (short circuit) and the mainboard no power on from on/off switch, even without door interlock. The door interlock deals with power on to mainboard?
Many Thanks. Marco
this could be board failure or interlock i can’t say which without seeing it
I found the problem. a fuse blown in main board. It has crashed because short circuit on connector from door interlock.
Do you have a circuit diagram for an Indesit WD12?
I unplugged the door interlock and didn’t note the order.
The wires are marked, MRL (red+brown), MRN (red) and MRC (brown+blue, red insulator).
Interlock has pins 1,2,3, switched on pins 2-3, heater pins 1-3.
Thanks for the video. Interlock works, I have no idea why it didn’t release which is how I broke the door handle off. Maybe I need to push on the handle to jiggle the interlock pin and pulling just jams the pin.
Don’t bother, sorted it. Connections are 1-N 2-C 3-L.
sorry we don’t have one for this model
Hi Thanks for the video,Can you help me with our hotpoint washing machineWT741the door lock locks but the light dos;nt ;light so the machine fails to start ,the door lock looks OK any advice would be appreciated.
you need to test the lock see video on how they work
Do you know why my Bosch dryer will not shut. It’s an old model but need to really bang the door to shut it. It’s in the garage wonder if damp caused fault.
you may have a broken handle or the lock may be faulty damp won’t do anthing
hello paul, I have a Kenmore commercial 110 washing machine and recently all the lights illuminated and will not shut off unless its unplugged. along with that the machine will not start. we insert the coins like normal and nothing happens when we press the start button. I would appreciate if you have any advice. thank you and sorry for the bother.
Hi Paul
Thanks for the interesting video. Always fascinating to know how these things actually work.
I seem to be having a problem that is common on the web with my Bosch WKD28540GB washer dryer. I am getting an E13 error code, which on this model is a door interlock error. However there seems to be no info on the web on how to fix this error.
I’ve checked and replaced the pressure switch and replaced the PCB with what I hope is a working one, but to no avail. I think my next port of call is to replace the door interlock but I don’t want to throw good money after bad – do you know anything about the above model and/or a particular way I should test the existing interlock to see if it’s the problem?
Thanks
Matt
there is a video on site on how to replace door locks
Thanks Paul. I replaced the door lock, but no luck still getting an E13 error. Any ideas?
Hi i have a Kelvinator KL600FL…KL60FLME i did washing and the door(latch) didnt want to open and washing still stucked in it.Please help me.
Hi, can anybody explain how Bosch exxel 7 WAE24468GB/17 door interlock works and how to test it? It works definitely by different way and the lock releases right after cycle without any delay for cooling down something. Thanks
Thanks for the very informative videos.
I know that it is either the door interlock or the door catch that is faulty, but is there a way of establishing which one? My Bosch washing machine will only start working if I press hard on the door catch until I hear a click and the machine starts filling with water.
I am no longer impressed by the quality of Bosch machines. At the same time my Bosch dishwasher pump constantly runs and won’t allow water to enter the machine. I was first going to take the left panel off and check that the float mechanisms were not stuck? It did the same thing a couple of months ago but started working again after I banged the sides a few times – this technical procedure no longer works. lol
i would first look at the door lock as this is most likely to go faulty
Hi there,
I have a Samsung WF1752WPW washing maching. Recently it has displayed dE error code which is related to inoperative door shut so the washer fails to start the cycle. I’ve replaced the interlock with a new one, and the wiring harness looks fine, but it still displays the dE error and not able to start the cycle. Any idea what could go wrong here (mainboard?!!)? Cheers
Hi, Paúl i have a speed queI have front loader it read door on display i change lock but still have door diplay where should i look nexo. Thanks
Thats speed queen
Hi I’ve got a servis washing machine.if I set it to a program and press start the light stays on waiting for the door to lock.after about 30 seconds the light starts flashing and doors not locked still.ive fitted a second-hand interlock and its just the same.
HI, I have an Electrolux front load dryer that sometimes opens during the drying cycle, what should I look for?
Is the fault code e13 100% for the door mechanism for the Bosch WKD28540GB, I’ve been following allsorts of audience and I’ve had the pump out and everything and still no luck,
Some sites say is it the pump others say it’s the door latch, I just need to know what the problem really is so I can fix it.
regards
rob
Hi, I have a hotpoint aqualtis washing machine which has started to trip my kitchen sockets when it’s plugged in. The door which usually opens when unplugged/switched off won’t open at all. Would this indicate a problem with the interlock?
We have managed to open the door with a quick switch on at the socket and pull on the plastic lever in the washing machine kick-board.
All manufacturers use some kind of interlocks, forgetting the pain of having washing machine full of water and wet clothes.
If the lock was designed never to fail, maybe, but no its bound to fail and sometimes in spectacular fashion by short circuits etc.
Had one where resistor broke and neutral went direct onto live, 2 hours later a managed the brake away the interlock and open the door.
Bypass switch or bypass all together is my solution. The fact is to lock the door for safety, so kids cannot open the door during washing / spin cycle, but face it if you like your children keep them out of the laundry, they could drown in the sink too.
Hi friend, I have a indesit wixl 105 washing machine , the door lock wire was short circuited and related transistor totally burned out from pcb (space of the transistor is “09” , so not effected other components
Now I can’t read this transistor details Please help me. I’m waiting for your replay. Thanks
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Appliances Engineer
AWM 8121 Front Loader
Machine has played up for some time.Drain Pump was definitely super worn out.Replaced it ,and the pump will run and empty test water from bowl.
But I am getting a F 11 code, and cannot get other functions. I strongly suspect the door switch is faulty..
However I’d like to rule out anything further up or downstream in the circuit.Have taken out the switch.
It has 3 terminals ,3 , 4 and 5 (6 is blank).
(I am new to multimeters,never test live stuff)
What is the simplest switch test procedure with multimeter? (which terminal is which, Com what should each position read ?
Should the switch click ( not ‘live’ ) when I push the sliding mechanism inwards?
Switch is reasonably inexpensive and easy to replace,but if I need circuits boards machine is off to white goods heaven, so I’d like to rule it in or out.
Cheers.
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Appliances Engineer
Hi Paul,
Great website!! Fantastic resource, thank you very much.
I have a Hotpoint HVF-344. I am interested in the door interlock, it has 5 pins. Do you have a wiring diagram for this type of interlock. DA266 is printed on the unit.
Many thanks,
Nick