How to Check the Wires in Bypass Garage-Door Sensors

Go to each of the sensors, and check the connection at the back of the unit. Some manufacturers use a removable connector to secure the wire to the sensors, while other manufacturers use a nonremovable connector. If your sensors use a removable connector, press it into the sensor to ensure that it is locked in place.

Place a stepladder under the garage door motor. Follow the sensor wires across the ceiling to the motor. It might be necessary to remove a lens cover to access the area where the wires connect to the motor. Most lens covers either unsnap from the unit or have two screws. If your lens cover is screwed in, use a Phillips screwdriver to remove it.

Unplug the opener power cord from the outlet in the ceiling. Loosen the terminal screws where the sensor wires connect to the motor, using the Phillips screwdriver. Pull each sensor wire from the motor, and ensure that the ends are not broken. Cut off any damaged end, and strip off a fourth inch of insulation from the end, using wire strippers. Reconnect the sensor wires to the terminal screws, and tighten the screws.

Examine the sensor wiring, starting from each sensor and following it to the motor. Check each spot where a staple secures the wire to the wall or ceiling. Look for signs of wear or cuts in the wire. If there is damage to the wire, replace it with new low-voltage doorbell wire.

Plug the motor power cord back into the ceiling outlet. If the sensors still do not operate, replace the sensors with new ones compatible with your door opener. Most home-improvement centers carry garage door safety sensors.