Customer FAQs Discover answers to the most frequently asked questions from ADT customers with the click of a button. 1. How do I replace a motion detector battery? When the batteries in your Motion Detector need to be replaced, a “zone trouble” indicator will appear on your alarm keypad and/or a “sensor trouble” indicator will appear on your ADT Pulse app. These indicators will help you determine that the motion detector’s battery is low. You should replace the batteries as soon as these indicators appear. The motion detector requires one CR123A 3 volt battery. This battery can be purchased at your local hardware, mass retailer or battery store. Some models may require two batteries. 1. Before you replace the battery, put your system into test mode to prevent false alarms.2. Visit MyADT.com and select “My Alarm” from the dashboard. 3. Once you click “My Alarm”, a menu will appear. From the menu, select “System Management."4. Select “place system on test.” (Note: You can also call 800-ADT-ASAP to put your system into test mode.) 5. To change the battery, first remove the screw in the motion detector. The screw may be located on the top or bottom. Use a flathead screwdriver to press the tab on the bottom of the motion detector. 6. Replace the battery, observing the proper polarity. Then, replace the motion sensor. Next, reset your security system by entering your code into your system and hitting off twice. 7. Remember to remove the system from “test mode.” 8. Go to MyADT.com and click on “My Alarm” From the System Management option, select “Stop Test“ to remove the system from test mode and restore operations. Watch this video to learn more.