Turn off the power to the fixture to be removed at the main power panel.
Place a ladder under the fixture to be removed and climb up to the fixture.
Unscrew the mounting screws and remove the face panel of the fixture. Also remove the screws from the mounting plate under the face panel and pull the fixture out away from the house.
Label the wires before detaching the old fixture. This will help avoid confusion when attaching the new motion detector lights. Locate the wire nuts holding the fixture wires and the house wires together and remove. If the wire nuts are still in good shape, they can be reused with the new light fixture.
Unpackage the new motion detection light fixture and take a moment to familiarize yourself with the wiring of the new fixture.
Twist the ends of the fixture wires with the appropriate house wires. Make sure the ground wire of the fixture is attached to the ground wire of the house.
Attach the wires with wire nuts and push the wiring into the house behind the mounting plate of the fixture.
Attach the motion detector light to the mounting plate with the screws provided with the light.
Cover the base of the light with the face plate and secure it with screws.
Turn the power back on to the fixture and turn on the switch to test the light.