How to Repair a Motion Detector Light

A man conducting repairs on a set of security lights.
  • 1 hours
  • Beginner
  • 0-30
What You'll Need
Clean cloth
Spare bulbs

A motion detector light is a security device that can be installed outside any home. The sensor works by detecting motion in its field of vision, which will cause the light to turn on. This can be a problem if the light is over-sensitive and is triggered by cats, small insects, or even stray dust moving in a certain manner. This problem can be overcome, but there are a number of other faults in which the motion detector light can suffer. Rather than taking it back to the shop, or even replacing it with a new one, you can try a few troubleshooting tips and see if you can repair your troublesome light.

Step 1 - Fix a Light That Won't Turn Off

This is a more common problem than you might expect, particularly after lights have been damaged in some way—for example, by an electricity surge. If you find that after resetting all the other electrical items in your home, your motion detector light is still shining (and there hasn't been any motion), then you can conclude that it too has been affected by the surge and needs to be reset.

If the light is wired into an electrical junction box, turn off the power at the main breaker to eliminate any danger of shock or electrocution before removing the light from the wall, and take out your instruction manual. This should have a list of all the buttons featured on the light, including the reset button. This will usually be red (and might even be marked "reset"). Press this until the light turns itself off. If clicking the reset button doesn't help, then you may find that running a cleaning brush over the surface, or even pushing a piece of paper down the side does the trick.

Step 2 - Fix a Light That Still Won't Turn Off

Another reason for the motion detector light not turning off is cold weather. As with everything to do with the cold, motion detector lights can be seriously damaged by frost or ice. When frost lands on the contacts, this can make the light freeze so that it can be stuck on the on position. Remove your light from the wall, and leave in a warm garage, or even by a radiator, until it goes off.

Step 3 - Fix a Light That Won't Go On

The opposite problem can actually be caused by the same reasons. However, if you have tried the above methods for getting your light to turn off and haven’t succeeded, then you should consider whether the light contains a damaged photocell. This part will either need a replacement or it could simply be dirty. The motion sensor, which triggers the light, should be cleaned regularly to avoid it becoming clogged. You can also simply increase the sensitivity of the sensor, as this will solve the basic problem.

Step 4 - Try Other Simple Repairs

Sometimes, the easiest repairs can solve major problems. If it seems like the motion sensor light has given up the ghost, then you should try cleaning the sensor first, and then remove the old bulb from the light and insert a new one. It is surprising how many times changing the bulb fixes a troublesome motion detector light.