questions about which part controls the lights off delay for the trunk

Are you talking about the trunk light?

yes...my trunk light stayed on for about twenty minutes

Okay, I just gotta ask. How do you know your trunk light stayed on? You didn't lock someone in there did you?

Page 4-56 of your owner'* manual explains how to customize vehicle settings. Page 4-60 explains how to change the timing for exit lighting delay. If you don't have a copy of the manual, you will find one here:

http://www.buick.com/content/dam/Bui...ner-Manual.pdf

pulled into garage, popped the trunk, turn off the key and got out to unload...came back later and it was still on...prior to that it went off after a short time...I did check the manula...I was asking what part number controls it so I could buy that part # and replace the part that controils the timer for the trunk

There is no timer. The switch in the trunk only turns the light on when the decklid is open, and off when it is closed. If you leave the trunk open the switch remains on. Your car has a battery saver feature that will shut off power to interior lamps and the trunk lamp 10 minutes after the ignition key is turned of. The car'* electric power management system may decrease this time period if your battery is low, which is probably why you experience variance in shut off times.

Try leaving the driver'* door open instead of the trunk. The interior lights will shut off in 10 minutes or less, depending on battery condition.

This is all explained on pages 4-13 and 4-14 of the owner'* manual I provided a link to. If your manual is different, look in section 4 (Features and Controls).

In short, I do not believe there is a problem in what you are experiencing.

I suspect that I just didn't notice it before...thanks for the info...I did put in a new battery(pricey!) and I suspect all is well as it does go off after a short time...probably 10 minutes.

Glad I could help. Let us know if there is anything else we can help with.