To change the fog lights in a car, locate the fog light assembly, remove the wire harness connected to the bulb and twist the bulb counter-clockwise to remove it. Connect the wire harness to the new bulb, and place it in the retainer.
Refer to the owner's manual for the vehicle to determine which type of fog light to purchase, and disconnect the battery terminals if it is recommended in the owner's manual. Remove the shroud behind the front bumper to locate the fog light assembly, and remove the wires connected to the fog light by gently pulling the wire harness off the bulb.
Twist the bulb counter-clockwise to release it from the assembly, and set the old fog light aside. Connect the wire harness to the new fog light, and set the new bulb into place by turning it clockwise to secure it. Reattach the shroud if necessary, and turn the lights on to test the new fog lights.
When updating fog lights to an LED version, choose an LED light that is recommended for the make and model of the car, and refer to the installation instructions on the bulb packaging to ensure the fog lights work properly after the installation is complete.