DIY, change the tail light assembly on your Mercury Sable, the model made in the years 2000, 2001, 2002, 2003, 2004 and 2005. The replacement procedure for this part is simple and it will require an 11 mm wrench and about 15 minutes of your time.
The repair starts in the trunk, where you need to remove a thumb screw, like the one in the picture below. By doing that, you will be able to pull up the plastic trim that covers the rear, bottom side of the trunk and you will gain access behind the tail light.
Now you have to remove the four nuts that secure the lens, as you can see in the next image. You can do it quite simply, using an 11 mm wrench. Loosen them a little bit and then carry on by hand.
After you do it, you will have to unplug the harness that powers the light bulbs and then force the rubber plug through the body of the car (see picture below). This will help you to remove the old tail light completely.
In order to install the replacement, you might need to move the light bulbs from the old assembly to the new one. You can do it by twisting their sockets counterclockwise. Then, insert the new lens into the body of the car, secure it with the four nuts and put back the plastic panel in the trunk to finish the repair. These are the steps you can follow, if you plan to remove and replace the tail light assembly on your Mercury Sable, the model produced between the years 2000 and 2005.