Motion detector lights feature a motion sensor that's sensitive to electrical surges or power blinks. Occasionally, after a power blink, the motion sensor light will remain in the on or off position. While it's logical to think that the light fixture is broken, sometimes all that's required to get it working properly again is for the motion sensor to be reset. Resetting the motion sensor only takes a few minutes, requires no tools, and anybody can do it.
Turn off the circuit breaker that powers the motion sensor light for a minimum of 30 seconds, then turn it back on. This will often automatically reset the sensor for many models of motion detector light. Some models require the breaker to be off for as long as an hour to reset the motion detector.
Turn the light switch on, turn it off for two seconds and turn it back on again. If the motion detector light is fed by a wall switch, this often will reset the detector.
Turn the light switch on and off rapidly approximately four times. The light will eventually stay on continuously. Once the light is on, turn the switch off, wait five seconds and turn it back on again. The light should stay off and the sensor should be reset.