Outdoor light on sensor doesnt turn on?

I have a outdoor light that is on a motion sensor.The light came with the house, so I am not sure how to set it up. It was working fine for some time and then the light stopped working suddenly. Changing the bulb didn't help. I went through the test settings and the light turns on when I switch the setting to 'TEST', it stays on for sometime and then turns off, never turns back on again until I hit 'TEST'. Can anyone give me ideas on how to figure this out before I call the electrician. Appreciate our ideas.Outdoor light on sensor doesnt turn on?It has to be the motion sensor. It is very easy to change. Buy a replacement and make sure the power is off. Wiring: All whites go together, Black wire that is is your box that goes through the wall goes to the black on the motion sensor, The red on the motion sensor goes to your lamp sockets. In test mode you can adjust the settings on how sensitive you want it. Test mode will work 24 hrs a day and only stay on for a couple of seconds.Outdoor light on sensor doesnt turn on?You will most likely need a new motion sensor. They do stop working, and from your description of the problem I would say that is the case.They are easy to replace, but make sure the power to the light is off.Outdoor light on sensor doesnt turn on?a new one will cost less than repairing the old unit.Outdoor light on sensor doesnt turn on?Have you tried to reset it? Turn the switch that goes to it off, count to 15 then turn it back on. Mine screws up from time to time and this takes care of it.