There is a switch by the trunk lid and sounds like it needs replacing.
The socket size for the trunk tail light on a 2001 Buick LeSabre is 7mm. Bulbs can be purchased at most local automotive repair stores.
I think the light assembly screws out from the inside of the trunk.
Should have an access panel inside trunk
open trunk lid and locate the trunk light switch.push switch to see if light goes off. if light does not go off, replace switch. if light does go off, adjust switch to where trunk lid operates switch when trunk is closed
is it in the rear spoiler? Thru the trunk, light socket is right below rear window
From under the back deck inside the trunk. Hope you like standing on your head...
power = light green ground = black
You must remove the entire tailight panel - remove trunk liner and the recessed nuts.
It may be due to a bad alternator. If the alternator has a bad diode it will draw battery power when the car is off. Another possible draw is the trunk light. The trunk light works with a sensor that is mounted to the curved bar on the left side (drivers side) of the trunk. This sensor sometimes slides out of adjustment and keeps the trunk light on when the trunk is closed.
I believe that one is accessed thru the trunk; lift the carpet out of the way and you should be able to remove the assembly.
Immidiately to the left of the steering wheel, below the traction control switch/twilight sentinel/interior light dimmer controls. Note that the trunk button can be disabled by a switch in the glove box or another switch in the trunk on the locking mechanism itself.
you either have a short or possibly your trunk light is on when the lid is closed.