Learn everything you need to know about safety sensors for garage door openers. We’ll talk about definitions, why they’re important, how to replace defective or damaged sensors, and why you can’t bypass them.

There are two safety sensors in a garage door opener system. The first is located on the receiver, while the second is located on the transmitter. You can easily tell them apart by looking at the connector cables. The receiver will have a black and white cable, and the transmitter has a solid white cable.

The door will always open, regardless of whether the sensors are working or not. However, Sectional Industrial Doors for the door to close, the sensors must be both connected and working properly.

Why sensors are important

Because sensors tell the garage opener to open or close, they are important components of the system. They are primarily included to protect small children from getting crushed under the weight of the door. However, they are useful for a variety of reasons and situations like:

protecting animals from injury

preventing damage to user’s car

stopping the user from damaging the door

How to replace defective or damaged parts

While it is possible to repair these parts yourself, most people choose to replace them. When purchased, most come with brackets and a limited manufacturer warranty.

Assembled, the sensors are approximately 3 x 10 x 9 inches, and weigh an average of two pounds. They are typically sold in pairs for around $40. To replace the defective or damaged parts, you’ll need to locate the two sensors.

Remember, the cables on each sensor Garage Door Opener Range are identified like this:

receiver: black and white cable

transmitter: white cable only

Start by unplugging the power supply to the opener. Then, unwire the defective or damaged part(s). Re-wire the parts according to the manufacturers instructions and turn the power supply back on.

Why you can’t bypass the system

For safety reasons, the system should never be bypassed. Fortunately, the electro-mechanical design actually prevents you from doing so. To understand why you cannot bypass the system, you can try a simple experiment. You’ll need the following items:

receiver sensor

transmitter sensor

extension wire


voltage meter


Start by suppling power to the opener (without the sensors). Use a voltage meter to measure the signal and determine the voltage for each port on the opener.

Using the extension wires, you can “force” opening by simultaneously touching them to ports 1 and 2. However, when you try to “force” closing by touching the wires to ports 1 and 3, nothing happens.

By using the oscilloscope and voltage meter, you can see that there is no signal generated when the sensors are not in use.

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