How do you replace the tag-illuminating light bulb on a 2003 Mitsubishi Galant?
You can access the bulb for the license plate illuminator by popping the trunk and looking directly behind the plate holder on the trunk-lid itself. There should be a swist type quick release plug that holds the bulb in place. (similar to the third tail-light on models without the spoiler)
Assuming it is the same as a '99 Galant: you go into the trunk and unscrew the three plastic caps that are holding the fabric-covered partition on on the side of the tail light that needs the new bulb. Then, undo the nuts holding the bolts on. There is a plastic-covered bolt there - push on that and it pushes the entire tail light assembly out. Then, undo the bulb holder and replace the bulb.
2007 Mitsubishi Galant tail light bulb replacement: Purchase the correct replacement tail light bulb(s) first, before disassembling the vehicle. See sources and related links below for replacement bulb information. Then consult your owner's manual for the tail light bulb replacement procedure. As simple as it sounds, the owner's manual is the best place to start for bulb replacement instructions and illustrations. You may want to consider replacing both left and right at the same time…