The Toyota Prius hybrid automobile comes equipped with a set of auxiliary fog lights. The fog lights are mounted low, beneath the marker lights, to illuminate the road when fog is present. When the car's low beam headlights are turned on, drivers can turn on the car's fog lights, using a lever on the left side of the steering wheel. The lever also controls the regular headlights. The fog lights will not operate in the high beam mode.
Remove the engine undercover from below the fog light you need to change. The cover is secured with bolt on the front side and a plastic clip on the outer-rear of the cover. To remove the clip, reach into the front wheel well and grasp the clip. Depress it, and push it down out of the cover.
Reach up through the space the cover conceals, and grasp the fog light electrical connector. Depress the plastic retainer clip on the outside of the connector, and pull the connector off the fog light socket.
Rotate the fog light bulb socket counterclockwise to release it from the fog light housing, and pull the socket and bulb out of the housing.
Pull the old bulb straight out of the housing, and insert the new bulb.
Insert the bulb and socket into the fog light housing, and turn it clockwise to lock it into place.
Reconnect the electrical connections.
Replace the undercover. Replace the bolt, and push the clip up through the hole, locking it into place.
Make sure the ignition is turned to the "Off" position to avoid shocks and shorts.