xEM Access Controller on Liftmaster

I’m trying to connect an xEM Access Controller to my Liftmaster garage door opener following this video. The door opener I have is newer and has an LCD display and when I short out the terminals in the back it resets the opener. When I check out the voltage it’s 12v normally and drops to ~9V when I press the buttons. I say buttons because the big button actually actuates two microswitches on the panel. I am attaching pictures so you can see what I’m dealing with.

Has anyone used an xEM Access Controller with this type of garage door?

Can you peel off/back the black cover so we can see the rest of the PCB and share a photo please

Sure thing.

Taking it off to get that picture turned off the switch. I think what’s happening is that the wires provide power to the switch but it connects to the opener wirelessly. Which would explain why shorting them out reset the switch since it was losing power.

Yes this is like a dumb HVAC system supplying power to a digital thermostat through the temperature control wires. You can’t just short these because the device is “smart”. What you will have to do in this case is find this actual micro button switch on the PCB and carefully solder to either side of that switch only to short those paths that the switch normally shorts when you press it.

What do these buttons do?


EDIT: Yeah, What Amal Said :arrow_up:

The bottom two make sure it’s installed in the case, the top two are the actual “open” buttons.

Thats the bugger you want!
Do BOTH Open?

My guess would be the buttons at the top are the ones you would want to focus on. You really only need to do one of them of course…

There are four posts on the switch, two of them are one side of the switched connection and two of them are the other side. There are four of them for stability and attachment to the pcb. The easiest way to test this is to simply use a paper clip to short two of these four connections together and if you short them and the door opens their closes then these are the two posts you need to solder the wires to that will lead back to their access controller relay.

:partying_face: It’s working!!!


Turns out that EITHER would open. No idea why there’s two!

There are two because the plastic “button” you actually press down on is so wide and it’s easy to put a switch on either side vs trying to balance the whole plastic thing on a single switch in the center… it would also cause stress on the microswitch if you normally press the plastic button on just the side and not dead center… better for longevity etc.


Is that a custom enclosure for the antenna?

I found it on Thingiverse: Coil Cover Plate - xEM Access Controller v2 by PulsarForce - Thingiverse

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Nice, 3D printing is one of those categories I never got into. I may have to start looking.

It’s awesome! The possibilities that 3D printing opens up are endless!

You did indeed

here is the relevant thread

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You might want to look around for places that have them for use. I’ve seen them in libraries, and you can find maker places (kinda like a gym membership, but with cool toys instead of sweaty machines).

For ex,
If you’re close to Wichita, try this.

Look under events and it has a 3d printing class on July 7th.

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