The parking lights contribute to the overall safety of the Cadillac CTS. If the parking lights are not functioning properly, you should replace them as soon as possible, not only for safety reasons, but because police in many states issue citations for driving a vehicle with faulty lights. Replacing a front parking light on your CTS only requires a new 3157 bulb, which can be purchased at most automotive parts suppliers.
Park the vehicle on a level surface. Turn off the engine.
Remove the four pushpins located on the underside of the protective shield on the front of the vehicle. Remove the protective shield from the vehicle.
Reach behind the front bumper area from under the vehicle to access the lamp housing.
Remove the largest bulb socket from the housing by rotating the socket counterclockwise. Disconnect the electrical connector from the bulb by lifting the two plastic clips at the base of the bulb.
Pull the burned-out bulb out. Replace it with a new 3157K type bulb by pushing the new bulb directly into the socket. Reconnect the electrical connector to the socket. Place the socket back into the housing. Rotate it clockwise to secure it in place.
Reattach the protective shield to the front of the vehicle by reinstalling the pushpins.