Garage Door Open Indicator Light




About: Just a guy who likes building things for my family.

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.



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35 Discussions


25 days ago

Really cool - this inspired me to make one. Thanks

1 reply

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


5 years ago on Introduction

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.


5 years ago

Cheers, excellent tutorial.


6 years ago on Introduction

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...


Reply 7 years ago on Introduction

Craftsman Wireless Garage Door Monitor

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

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.


6 years ago on Introduction

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.


6 years ago on Introduction

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.

1 reply

Reply 6 years ago on Introduction

If you do a search on Instructables or Google for that matter you should find plenty of tutorials on how to size resistors for your needs. Please post a picture of your final product when you get it completed.


7 years ago on Introduction

you might be able to piggyback this led/switch off the power that runs to your wall switch or the saftety beams on your garage door opener


7 years ago on Introduction

very good instructable

I made a similar indicator circuit using a doorbell switch with an internal light - this was way before LEDs were widely available (at least to me) about 30 years ago - a little bit of switch disassembly and rewiring it to make the light independent of the switch.
The doorbell switch now activates the garage door opener and the light comes on when the door opens - whole thing runs off the existing door bell transformer using repurposed 4 conductor telephone corded.
I have 2 of these modified switches - one by the front door and one by the rear allowing me to open and monitor the garage door from either spot.

Maybe I'll update to use LEDs :-)

1 reply

7 years ago on Introduction

I did something really similar to this.
Couple differences; I used magnetic reed switches instead of a physical switch because I was a little afraid that snow would get into the switch in the winter and freeze it solid. And also I wasn't sure about how the roller bit on the switch would handle the joints on the door.
I didn't have any normal wire for this either, so I pulled individual pairs of wire out of a Cat5 cable that had been chewed up by the cat.
And lastly since I don't have any easy power sources in my garage, I run mine off of a 9v battery. I put a second LED on the circuit inside of the garage so that I could double check that the battery hadn't gone dead before I shut the garage door.

2 replies

CAT5 chewed up by the cat. LOL

Thanks for the instructable. I'd seen another one similar on here but never got around to it. You may have motivated me to get it built this time around.


7 years ago on Introduction

I've read so many cool instructables, but never actually done one. Little skill, inexpensive supplies, really clear instructions, this one is for me!

I'm in the habit of closing the garage door when I come in, but sometimes I leave it open for hubby or go out the garage and come into the house from the deck after doing yardwork. Next morning, I'll see that anyone could have come in and entered the house overnight.

As it's a safe neighborhood (and nothing exciting happened overnite), I'm more worried about a small animal coming in during a cold evening and getting under the hood and next to a comfy warm engine - I would not want to see, or hear, the results if I turned on the engine under those circumstances!