beeping in dash when I turn off engine

It is similar to beeping if I leave lights on (If I do leave lights on it is louder). It varies in loudness and sometimes goes away.
thanks in advance.
jim

Is the chime that sounds when you leave the ign key in the cylinder (engine off), and open the driver’s door?
car alarm Installed? Aftermarket radio? I got a pioneer radio that beeps when the car is shut off, to remind you to remove the faceplate, but I shut that feature off

The only yes is to aftermarket radio which I have had for a few years. I now have access to shop diagnostic information that suggests the problem might be a faulty audio alarm module. I took it out and the beeping stops but I also lose the 'forgot to turn off headlights' warning.
I see no resource for a replacement audio alarm module.
thanks for your response
jim

Is it possible that the ignition key cylinder ‘thinks’ you left the keys in it, engine off, door open?
Or does it ding as soon as you shut car off, before you open the door?

it dings as soon as I shut car off, before I open the door, and will ding forever, except I have noticed that if I disconnect battery and reconnect a few hours later the dinging is gone. As I mentioned a shop manual diagnostics suggested bad module but??. It was interesting that turning on headlights made it ding louder and faster.
I leave the dash lights on high to remind me to turn off headlights.