Garage Door Open Indicator Light





Introduction: Garage Door Open Indicator Light

This Instructable will explain how to make a simple flashing LED indicator to let you know when your garage door is open.

At the end of the day I was always checking the overhead garage door on my house to make sure it was closed.  I decided to install a flashing LED light that would let me know when it was open.  This has saved me many trips down the steps from upstairs to check the garage door before going to bed at night.

Step 1: Tools and Materials


  1. Blinking red LED from Radio Shack.
  2. SPDT Switch with 3/4" Roller Lever from Radio Shack.
  3. Miscellaneous DC Wall transformer.
  4. A resistor for the LED.
  5. A piece of scrap aluminum.
  6. Miscellaneous wood screws and machine screws as needed.
  7. Miscellaneous two conductor light gauge wire.


The tools I used on the project were as follows:
  1. Cordless drill
  2. Screwdrivers
  3. Hacksaw to cut aluminum material for brackets

NOTE: If you plan on using any tool for a project please make sure you are familiar with the tool and all of the dangers associated with it. If you are not familiar with a tool then you should ask someone who is to show you the proper way to use it. A lot of communities have classes at local colleges on the proper use of tools and machinery. There are also local woodworking clubs that offer classes at very reasonable rates for beginners. I highly recommend using these resources for your safety and for the most efficient use of the tool.

Always wear eye and hearing protection.
Always work safe with the proper safety equipment and guards on your tools.

Step 2: Determine Where to Install the Garage Door Switch

Like I mentioned earlier in the Instructable, I used mostly parts I already had for this project.  The switch I used was a roller contact lever switch.  I decided the best place to mount the switch was above the door .  That way it is out of the snow or rain if it was mounted lower along the side of the door.  Also, there is little chance of hitting it by accident.

The switch is wired to the Normally Closed contacts so that there is no through circuit when the switch is depressed while the garage door is in the open position and the LED doesn't receive power.  In order to do this I had to add a piece of aluminum on the top edge of the garage door.  When the garage door closes the aluminum moves into position against the roller on the switch.  When the garage door is open the lever is released and the switch goes into the closed position and power is supplied to the LED.

I made the mounting plate for the garage door out of some extra pieces of aluminum that I bent in a vide and then cut off with a hacksaw.  They aren't pretty, but they work great.

Step 3: Determine Where to Install the LED Indicator Light

I wanted to put the indicator light in a place that wouldn't be noticeable, but would still be visible.  I decided to put mine in the inside of a security system box.  The location is at the base of my steps so I can see the flashing red light from upstairs.  I can also see it from my kitchen.

The box is also located on a common wall to the garage so I didn't have to run the wires very far.

The security box also has enough room in the back of it to fit the LED and the light can shine out through a few of the vent openings in the side of the box.  When the garage door is closed and the LED isn't flashing then there is no way to see the LED.

Step 4: Find an Outlet to Power the LED

Find an outlet somewhere between the switch and the LED where you can plug in a wall transformer to power the LED.  You can also power the LED with a batteries, but if the batteries run out and the garage door is open then there will be no power to light the LED.

I used a cheap 3 volt wall tranformer from left over from another project.

Step 5: Run the Wiring Between the Light, Switch and Outlet

The circuit in the picture below shows the approximate layout for the wiring.  Run the positive lead from the wall transformer to the switch on the garage door.  From the switch run a wire to the resistor for your LED and then the LED.  Then run a wire from the negative lead of the LED to the negative lead of the wall transformer.

Make sure you use a resistor with the LED.  You will need to determine the best resistor for the LED that you are using.  I am not going to go into the specifics on that here as there are tons of tutorials on Instructables and other places on the internet.  Here is a link to an online LED calculator.

Step 6: Test the Switch

If you did everything correct then you should have an LED that lights up when you open your garage door.



  • Pocket-Sized Contest

    Pocket-Sized Contest
  • Pro Tips Challenge

    Pro Tips Challenge
  • Paper Contest 2018

    Paper Contest 2018

We have a be nice policy.
Please be positive and constructive.




I'm glad I found your page. I have something similar, but I used a magnetic reed switch which stopped working after one relatively mild Texas summer. If you have set up your alarm system yourself, you can hook this up as an input to the alarm panel as monitor-only, or with the following characteristics:

- Do not use this sensor to prevent going into the ARM state

- Secondary entry delay of 4 minutes or so


I used this as the basis for my design. It was the contact switch, an LED, a 2 AA battery box, and some wire. Wired it all straight together and set it up. Works perfectly.

Cheers, excellent tutorial.

Has anyone tried to take the open/closed status off the indicator on the opener? My Liftmaster has 2 2-wire terminals from the eyes that are for telling open/closed. I've yet to put a meter on them to see what they show in terms of contact condition and voltage when open or closed, but I will check that out soon. Seems lime maybe the position condition is already there for us to steal...

I'm on the third floor and would love to figure out a wireless solution.

Any thoughts?

Craftsman Wireless Garage Door Monitor

Other types are available. Check your local home supply store.


What's the fun in that?! :>)

I use X10 senders/receivers with magnetic reed switches (two-door garage), so there are no batteries and I can put the receiver in the appropriate spot. X10 is still available on-line and inexpensive.

Wonderful tutorial! I've been thinking on how to do this many times for peace of mind. The adaptation I'm going to have to make though is that my garage is detached.

Great tutorial. I was going through my crate of old misc wires, phone line, transformers. I found an old indicator light for a phone line, with a jack. I was thinking of using this as my light, with a 12v 1a transformer. I am a bit lacking on the resistor knowledge, as I have not used them for quite some time. Where can I find a source for determining a resistor for the above adaptations? Thanks in advance.