A garage door opener is a convenient way to open your garage door. At times the garage door opener can malfunction and the garage door will not open or close. The opener can self diagnose any issues. It informs you of an issue by flashing the diagnostic LED light a certain amount of times. Counting the number of times this light flashes will allow you to know the exact fault.
What is the most common reason the lights flash on my garage door opener and my garage door is not closing?
PROBLEM: The safety sensors are not properly aligned or an object is obstructing the sensors.
SOLUTION: To fix the flashing lights simply remove the obstruction or realign the safety sensors.
When a problem is found on a garage door the “Learn” button and or diagnostic LED will flash a certain amount of times and then pause informing you it has found an issue.
NOTE: The LED light that is referred to in this article is the small light that is located on the opener near the adjustment, “Learn”, or “Program” buttons. You will need to use a ladder to access this area.
Here is a diagnostic list (flashing light codes) for the following garage door opener brands (Liftmaster, Chamberlain, Sears). These 3 opener brands are diagnosed in the same way.
GARAGE DOOR LIGHT FLASHING – WHAT DOES IT MEAN?
1 – ONE LIGHT FLASH
Safety sensors wires open, broken or disconnected.
2 – TWO LIGHT FLASHES
Safety sensors wire shorted or black/white wire reversed.
3 – THREE LIGHT FLASHES
Door control or wire shorted.
4 – FOUR LIGHT FLASHES
Safety Sensors slightly misaligned (dim or flashing LED).
5 – FIVE LIGHT FLASHES
Motor overheated or possible RPM sensor failure. Unplug to reset.
6 – SIX LIGHT FLASHES
Motor Circuit Failure. Replace Receiver Logic Board.
GARAGE DOOR LIGHT FLASHING DETAILED PROBLEM & REPAIR
1 LIGHT & 2 LIGHT FLASHES
PROBLEM: One or both of the indicator lights on the safety sensors do not glow steady.
- Inspect sensor wires for a short (staple in wire), correct wiring polarity (black/white wires reversed), broken or disconnected wires, replace/attach as needed.
- Disconnect all wires from back of motor unit.
- Remove sensors from brackets and shorten sensor wires to 1-2 ft. (30-60 cm) from back each of sensor.
- Reattach sending eye to motor unit using shortened wires. If sending eye indicator light glows steadily, attach the receiving eye.
- Align sensors, if the indicator lights glow replace the wires for the sensors. If the sensor indicator lights do not light, replace the safety sensors.
3 LIGHT FLASHES
PROBLEM: LED is not lit on door control.
- Inspect door control/wires for a short (staple in wire), replace as needed.
- Disconnect wires at door control, touch wires together. If motor unit activates, replace door control.
- If motor unit does not activate, disconnect door control wires from motor unit.
- Momentarily short across red and white terminals with jumper wire. If motor unit activates, replace door control wires.
4 LIGHT FLASHES
PROBLEM: Sending indicator light glows steadily, receiving indicator light is dim or flashing.
- Realign receiving eye sensor, clean lens and secure brackets.
- Verify door track is firmly secured to wall and does not move.
5 LIGHT FLASHES
PROBLEM: Motor has overheated; the motor unit does not operate or trolley is stuck on stop bolt = Motor unit hums briefly; RPM Sensor = Short travel 6-8″ (15-20 cm).
- Unplug unit to reset. Try to operate motor unit, check diagnostic code.
- If it is still flashing 5 times and motor unit moves 6-8″ (15-20 cm), replace RPM sensor.
- If motor unit doesn’t operate, motor unit is overheated. Wait 30 minutes and retry. If motor unit still will not operate replace logic board.
6 LIGHT FLASHES
PROBLEM: Motor unit doesn’t operate.
- Replace logic board because motor rarely fails.
To find more info about your garage door opener, below are PDF manuals for 3 top openers. Check your corresponding install and service manual if you need more troubleshooting help.
– Chamberlain Garage Door Opener Manual
– Liftmaster Garage Door Opener Manual
– Sears Garage Door Opener Manual
Garage Door Opener Troubleshooting and Repair – How to fix common problems
Have questions about your garage door flashing a diagnostic light? Please leave your comment or question below explaining your garage door issue.