Skip to content

How to Fix FC on Your ADT Alarm System

This article is a collaborative effort, crafted and edited by a team of dedicated professionals.

Contributors: Muhammad Baballe Ahmad, Mehmet Cavas, Sudhir Chitnis, and Zhen-ya Liu.

✓ Verified & Tested Information

Most homeowners don’t know how to fix a problem with their ADT security system. Here’s a blog post that will show you how to fix an FC error on your ADT system.


Your ADT Security System is designed to send a signal to the monitoring center in case of an emergency. However, if your system starts displaying a “FC” or “Failure to Communicate” signal, this means there is an issue with its connection to the monitoring center.

Fortunately, resetting the system usually solves this problem and the FC signal disappears. But if the signal persists, then it could indicate further problems with your ADT Security System that needs to be fixed. This guide will help you troubleshoot and repair any issues that may be causing your FC error.

Identifying the Problem

If you have an ADT alarm system, you may have seen an error code pop up on your screen signaling a problem with your security system. One common error code is the FC code, which is an indication of a problem with your system’s connection to the ADT monitoring center. In this article, we’ll look at what the FC code means, what could be causing it, and how to fix the problem.

Check the battery

To identify the source of the FC on an ADT alarm system, first check to see if the panel has a low battery problem. A low battery warning will show up in red on the control panel display, and this will explain why the FC code is showing. Low batteries can cause false alarms as well as other issues with your system functioning properly. To fix this, simply replace your batteries according to the instructions in your user’s manual and then test to make sure everything is functioning properly. If there is no issue with a low battery, you may need to look for other sources for why your system has started experiencing FC errors.

Check the power supply

When troubleshooting an issue with a home security system, it is important to first check the power supply. In order to determine whether the lack of communication within your ADT alarm system is due to a power issue, you should start by checking for any loose connections and verifying that the battery isn’t dead. The alarm system should be connected to a constant source of power such as a wall outlet, so ensure that the plug is securely inserted into the outlet. If your electricity is out due to utility issues or an overload in the circuit breaker, this could precipitate an FC code.

The majority of ADT systems will utilize either a 12V 7Ah or 12V 9Ah backup battery when main AC power is unavailable. If the AC has been out for more than an hour, then check if this back-up battery needs replacing by testing its voltage with a multi-meter. Ideally, you should test the voltage after 48 hours without AC power. If it’s below 10volts then it’s time for it to be replaced as batteries can no longer hold charges after this point.

One important thing worth noting here is that only non rechargeable batteries from leading suppliers should be used in Alarm Systems as numerous issues can arise from using generic brands or faulty cells specifically when dealing with ADT systems like an FC error code preventing communication with monitoring centers associated [with them].

Check the wiring

When troubleshooting Functional Check (FC) issues on an ADT alarm system, the first step is to check the wiring. If a connection or jumper wire is not correctly wired and/or secured, the system may be unable to complete its self-test or determine an issue with itself. To check the wiring:

1) Open and secure access to all power, communication, and any necessary alarm sensors. Ensure that all wires are properly attached to their respective terminals.
2) Visually inspect the cable for any physical damage or breaks that could disrupt communication along its length.
3) Inspect each terminal for any broken prongs or loose connections that could be causing a short circuit in the system’s circuitry.
4) Ensure all wires are of appropriate length with enough slack on both ends to allow for movement should additional hardware or devices be added in future installations.
5) Secure all covers after physical inspections have been completed, restoring power if necessary – do not connect and activate them until you have tested your system’s FC feature again and verified proper operation.

Troubleshooting the Problem

If you are experiencing a “FC” message on your ADT alarm system, there are a few troubleshooting steps you can take to try to fix the problem. This guide will go through some of the most common causes of this message and provide step-by-step instructions on how to resolve the issue. Before you begin, make sure that your alarm system is connected to a working power source and that it is properly configured. Once you have checked these two things, you can begin troubleshooting.

Reset the system

Sometimes your ADT alarm system may experience a failure due to an overload of signals, incorrect installation or wiring faults. The FC error on the ADT alarm system appears when it is unable to communicate with the monitoring center after you input their phone number. If you want to fix this problem, then resetting your system might be the best solution.

You can reset the system by unlocking it and pressing and holding the “off/test” button for 12 seconds until the yellow trouble light turns on. You should then wait another 30-60 seconds before releasing the button. After doing so, scroll through all of your zones to ensure they are all closed; if any of them are still open, press and hold the same button for 12 seconds again until successful. Once complete, try re-establishing communication between your alarm panel and monitoring center.

Check the sensors

If your ADT alarm system is showing a “FC” error message, it’s important to troubleshoot the problem in order to determine the cause. Start by checking the sensors. Make sure all of the sensors are correctly and securely installed by following manufacturer instructions.

All sensors should be connected to the same power source. If some of them are connected to different sources, move them all onto same power source or contact an Authorized Service Provider for further help. Also check that all wires are securely attached with no signs of damage such as exposure or fraying.

Ensure that there is no obstruction that could prevent proper signaling between the sensors and control panel. Make sure no furniture, paint, wallpaper or insulation materials have been added near/between any components since system installation – as this can inhibit proper operation of your sensors and result in a false alarm condition (FC).

Check the keypad

If your ADT alarm system is displaying FC (Failure to Communicate) on the screen, one of the first things you should check is the keypad. In some cases, the issue may be as simple as a slightly unplugged or malfunctioning keypad. Carefully inspect the connections between secondary keypads and any sensors to make sure all connections are secure.

If you find that the problem persists after verifying that connections are firmly in place, you may need to reset your alarm system. Try performing a disconnection test: unplug the alarm panel’s power cord, wait 10 seconds and plug it back in again. The display should temporarily clear before returning to its normal display mode. If it does not, try pulling out any backup batteries and let them sit for 10 seconds before reinserting them into place.

You may also want to perform a diagnostic test on your system with an ADT Diagnostic Scan Tool. This tool requires a PC connection and can help detect wiring issues or require programming updates associated with your specific model number of alarm panel in order to correct any issues with communication failures between sensors or keypads on your system.


In conclusion, when troubleshooting the FC issue on your ADT Alarm System, first ensure that the panel is powered up and operational. If this does not resolve the issue then test the connection between the panel and your internet modem. If there is an issue with connectivity then try restarting your modem/router or manually connecting to the panel using a laptop or tablet. If after these steps you are still experiencing issues then you can try resetting your ADT Alarm system to factory defaults. Lastly, if all else fails, call ADT and arrange for a service call from a qualified professional who can sort out the FC Issue. Remember to keep moving forward in finding answers to any of your alarm system problems!

How to Fix FC on Your ADT Alarm SystemCheckout this video:

Share this Article