Buick Lucerne Electrical Problems

As the engine starts properly, the battery is likely OK. Multiple malfunctioning accessories as you're experiencing, are most often a sign of a failing alternator, loose belt or defective cables or loose connections. I suggest you have trouble codes read to see if this points to anything specific, and if you also notice erratic behavior in the instrument cluster, this could point to a problem in the body control module.

Buicks tend to have problems with grounds, especially the ones for the BCM, my last Buicks seats would just quit working then would start back working, took me a long time to find the problem due to the intermittent operation, it was a ground wire under the passenger seat, and yes I did have to remove the seat and carpet on that side, after that I have found similar grounding issues and BCM connector problems. Do not rely on the dealer to find the problem cause they won’t go any further than checking for codes, and as it won’t leave a code that’s when they stop.

Site error, not posting answer

Yes, yes & yes....erratic behavior in the instrument cluster. Where is the body control module located?

Your vehicle has on the left side of the dash, after you get the lower panel off you should be able to see it.

Body Control Module (BCM). Hope that helps! Jim