chirping sound peterbilt

I have a 2016 Mack Automatic. I put it in reverse and it started making an ear piercing chirping. Even when i shut the truck off it was still making that noise. I had to wear ear plugs to drive it bavk to the yard. I mess with the ignition key and it changed pitch but didnt stop. Its coming from the dash not the motor???

 

Sounds like your low air/oil pressure alarm may be stuck on, perhaps bad sender? I know nothing about Macks but it sounds as if it must be electrical.

 

Could be anti theft/ driver tracking device as well. Ive seen lots of trucks with a small button in the dash you have to place your individual tag on otherwise it starts squealing after 1 minute of the key on.

 

That's a much more likely cause, especially on that new of a truck.