XEM Controller AND other Reqired Parts!


After watching Amal’s youtube video of his XEM access controller opening his garage door, it appeared he did not use a capacitor or diode as seen in previous posts. I only saw a simple automotive relay, XEM controller which was wired to power and wired to the garage door. Just trying to get some insight. Are they required for the garage door project?

I’ve seen the video of Amal’s bench test with a striker (XEM access controller), it is seen with a capacitor and diode. Is it safe to just use the simple automotive relay, XEM controller and power? or is it now recommended that a capacitor and diode be used?

Thank you for your input

The diode(s) are to protect the access control from damage. It will work without them, but over time it will fail. It could be a few months or a few days. If you don’t want to order those parts, plan to order another access controller when it dies.

The capacitor is to give you some time to open the door after you pull your hand away, because the access control shuts off the moment you remove the tag from the field. If you don’t want that quality of life improvement, you don’t need a capacitor.

This was the response I was looking for

thank you Satur9 Guru


To add to that, it matters what you’re hooking into. If you take a look at this thread its a pretty good guide and @Devilclarke 's drawings are spot on for how to hook into a garage door.

You’ll notice it doesn’t do the capacitor here, that’s because most garage doors are momentary switches, and the capacitor just generally acts as a way to hold the button down for a few seconds. If it works with a quick pulse you don’t need to spend the extra 30 cents on parts or time to make it a longer pulse.

If you’re hooking into a solinoid for a desk or door latch, you’ll almost certainly want to do the capacitor since it’s hard to get from the tag reader to the open fast enough otherwise.


To add to what @Dean said above the complete schematic diodes and all is further down the chain. As Dean said the capacitor is only required if you need a longer press on the button or are powering a door latch / solenoid directly.


Thank you for all the great responses! So I connected my xem controller and when trying to program (followed the instructions in the video that’s been posted), it doesn’t read the master fob but it does read the two other fobs included and my implant. Any ideas why it’s not reading the master fob to program? I’m trying to attached a video to show.

So can you confirm you cant enroll your xEM or NExT?

Just to be clear, you cant “switch” the xAC with the master disc, it is purely for programming*

*except with unusual circumstances

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Here is the video…

Not sure if it worth adding, when swiping the master fob or additional fobs, it does not open/close the garage door.

Correct, it does not seem to be allowing me to enroll it. My NExT implant is able to unlock my door, so I know it is not my implant.

Do you have another xAC?
Did you get it from DangerousThings?
Do you have a ProxMark3?

Have you cycled the power

Do you have any spare EM4xxx or T5577 (you will need to write EM to it ) cards to try to enroll

Also, if you are comfortable with doing it.
you could try holding the master disc to the antenna for 15+ secs it should wipe any associated tags/fobs/implants. (will you still be able to a access your garage without xAC)

If it doesn’t wipe them, then you may have a faulty/incorrect master disc.

If it does, then try to re-enroll the previous tags.

Looking at this video I don’t see a problem with the master or programming?

It’s normal that the master doesn’t make the LED light up, and your other fobs and implant seem to be working - am I missing something? Are you trying to add another tag?

Perhaps your issue is with the wiring after the xAC?

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good point, I read it as, it was working but just unable to add additional fobs or implant…

See where the red LED illuminates when you scan it? That is connected to / powered by the same circuit as the white output wire inside the case. You can double check this by installing a test light between the white output wire and the ground (black), should light up when scanning.

Looks like the unit is working fine.

Step 1, Make sure you’ve got the white wire and the black wire going to either 85 or 86 on your relay. Doesn’t matter which is which.
Step 2, Make sure the diode is in the correct way. Test for power before and after relay while scanning to confirm. Should have power on both - WHILE SCANNING. If you have power before, but not after, then you’re backwards.
Step 3, You should here the relay clicking when the red LED comes on.

If you succesfully complete step 3, then everything up to, and including, the relay is working. You need to check everything after. In that case, get us a good pic of your wiring and we’ll go over it with you.


I think I misunderstood your problem. The master ALWAYS act different on purpose. It is the only chip that will not light up the led or activate the xAC.

It’s only purpose is to let the xAC know that you’re enrolling the next chip it sees. (can also be used to erase all chips). It does nothing else. The xAC has no visible reaction to it, other than to enroll / or erase.


Hey @jlyon86, have you had any luck with your xAC / door issue?

New exciting project about to drop on the forum, would love your expertise. (Its a Big Project)

There are likely plenty of people here willing and able to help.
What do you need?

Recently purchased a 2009 chevy duramax shuttle bus, with the intent to convert it to an RV. The goal is to use the newer V2 version to activate the bus doors. There is a shuttle bus conversion on youtube that added a key fob to there system, not sure how to send you a link on here to that video. There is a window next to the doors that might act as a good mounting and hand to antenna scan point. The help I need is how to wire the Xac v2 to the key fob box? or maybe to just the doors? see this is where i am lost. any help would be amazing. thank you