Do it yourself, change the side marker light assembly on Ford Expedition, the model produced between the years 1997 and 2003. You will require a T20 torx driver for this particular replacement, a new side marker assembly from the local auto parts store and less than 15 minutes.
You will not need to remove the headlight to access the side marker. You just have to open the hood of your car and locate the T20 torx screw that we marked with the blue circle in the image below. You can remove it very easily using an appropriate screwdriver.
After you do it, you can simply pull out the side marker towards you. Behind it, you will notice the electrical harness powering the light bulb, as you can see in the picture below. Unplug it and release the assembly. You can also service the bulb at this time, if it’s needed, by twisting its socket counterclockwise.
Now you can install the replacement. Be careful how you align the side marker back on its place. Connect back the harness, push back the assembly into the car’s body and secure it with the screw. This is all you have to do, if you need to replace the side marker light assembly on your Ford Expedition, made between the years 1997 and 2003.