Motion-sensing lights automatically turn on the lights when motion is detected. In the event of failure, you may need to replace the fixture. Rewiring outdoor motion sensor lights is similar to wiring a normal, non-motion detecting light. Many jurisdictions and municipalities require any fixed lighting to be completed by an electrician. Check your codes for specific licensing requirements before beginning work.
Turn the circuit breaker off at the main panel.
Test the existing light by switching it on at the switch, turning the light's "Test" mode on and creating motion. Test mode is likely on the fixture itself. Test mode allows for motion testing in daylight. When you are sure the circuit is disabled, remove the existing fixture and discard. Unscrew it from the junction box plate with a screwdriver and twist off the wire nuts.
Connect the black sensor wire to the black Hothouse wire. Twist on new wire nuts. Connect the white sensor wire to the white Neutral house wire. Connect the green house Ground wire to the green Ground screw on the fixture with a screwdriver. The screw may be marked "GRND" or similar.
Attach the new fixture to the wall, using the enclosed screws and a screwdriver. Take care not to snag any wires between the fixture housing and the wall junction box housing. Turn the circuit breaker back on and test.
Keep any openings like the sensor bottom facing down to avoid water infiltration and a chance of electric shock.