If the Tilt sensor has lost its connection to the garage door controller, you can perform a manual re-pair on the Tilt Sensor.
1. Press and hold the main GDC button (located on the front of the unit) for 5 seconds then release
2. Make sure that it entered sensor pairing mode, look at the back of the GDC and refer to the LED, it should be blinking slowly at a rate of once per second
3. Tap the Tilt Sensor tamper switch once
4. The LED on the main GDC unit should stop blinking which should indicate that the pair was successful.