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How To Clear A “Com Fail” Message on Your Security System Keypad

By December 9, 2014 February 17th, 2021 No Comments

What Does “Com Fail” Mean?

A “Com Fail” message on your security system keypad means that a your control panel attempted to transmit a message to the central station and failed. This can happen for a variety of reasons. Most commonly, a loss of phone service due to a power outage. Even a temporary loss of power may result in a “com fail” message.

ADT Customers, please call your ADT representative. SHIELD Security can not assist you in clearing this message. 

Note: A “com fail” message does NOT necessarily indicate that your security system is not working now… It only means that there was a temporary loss of communication. Often, this happens in the middle of the night when your system is attempting to send a test message to the central station. So, in the morning, as you are leaving for work, you may see a “com fail” message on your keypad. Before you leave, take a moment to clear the message by following these steps:

How To Clear The “Com Fail” Message:

Clearing the “com fail” message is easy. It involves simply sending a signal through to the central station… Reset the cellular transmitter.

  1. Step One: SHIELD Security Systems clients, please call your local office.
  2. Step Two: State that you had a “com fail” and need to clear your alarm panel.
  3. Step Three: Give your false alarm password. (Your system will be put in “test mode” temporarily.)
  4. Step Four: Arm your system.
  5. Step Five: Open a door or window… Let the siren blare for at least 20 seconds
  6. Step Six: Silence the system by entering your user code.

Done! – Your system keypad should be cleared.

Other Common Issues:

“Com Fail” is one of several trouble messages that you may see on your security system keypad. Although it is concerning to see any trouble message, in most cases the problem is temporary and can easily be handled.

Below is a chart that shows some of the most common reasons of alarm system trouble.In some cases, you’ll be able to fix the problem yourself. For more complicated issues, however, you’ll need to schedule a service call for a professional service technician to assess and fix the problem.

While the the possible causes of a lit trouble light are endless, the most probable cause and solutions are outlined here:

Low Battery On Main Control Panel Normal control panel battery life is 2-5 years. Replace the battery in the control panel.
Power Supply Control panel outage, power outage to the house, loss of power to plug, transformer for the system is dead. Check the plug that the system transformer (a little 3″x3″ cube) is plugged into. It could be “dead” due to lack of power to the house, a tripped circuit breaker or a “popped” GFI plug (usually located in the basement).

Reset power; all should go back to normal (unless the transformer for the system went bad – If that happened, you’ll need a service call.)

Telephone Line Trouble Traditional “land line” systems are always looking for dial tone to control panel. If the house phone is dead this trouble condition will exist. Check to see if your phone line is working. You may want to contact your phone service provider to have them test it remotely.
Low Battery On Wireless Devices Normal battery life on a wireless device is 3-5 years. Replace the battery in the device that has a low battery or schedule a service call to have trained technician replace the battery. (We highly recommend replacing ALL wireless device batteries when one is showing up as “low.”
Communication Failure  “COM FAIL”


The control panel attempted to get a signal to the central station and it failed. First, determine if your phone line is working. (Have your recently lost or changed phone service?) To clear “Com Fail” message, call our office and have us put your system on “test.” Then, arm the system and open a device on your system (eg. window). Let the system go into alarm (actually making the siren sound). At this point, the system will send a signal to the central station and clear your communication failure. If this does not work, you’ll need a service call so that a trained technician can assess and fix the problem.
General Wiring Problems Some wiring from the control panel to the devices in the house is “supervised” for integrity. If a wire gets cut, chewed through by an animal or just breaks, this could cause a trouble condition on the system. There is usually nothing you can do to fix this trouble condition. A service call will be needed so that a trained technician can assess and fix the problem.


Main Takeaway:

If you notice a “com fail” message on your keypad, call us. Warning signs like “beeps” and “blinks” means that something is not quite right and should be fixed. Ignoring the problem or waiting until “later” isn’t the most desired solution. And, on behalf of all the security providers out there, please don’t wait til the day before you plan to leave for vacation to alert us to the problem! Chances are, your issue can be handled right over the phone. Worst case, a service call might be in order.

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