Horn honks when starting

[Zipoteloco]

New here, I have a 2014 Sierra crew cab SLT with bose system.

Couple days ago after installing a sub, every time i turn the ingnition swith to the on position, the horn honks around 3 times rapidly, the truck starts and warnig lights on the dash. I tried disconnecting all the power to the after market amp but it still doing it. Anyone has any idea why is doing this?

[20L8TSierra24]

Oops. Good luck figuring it out though

[Zipoteloco]

Anyone has ever had this issue before???

[ZakAttack]

Z,  I have this problem now in my (new to me/used)2015 3500 Denali HD. I can’t figure it out and it’s driving me nuts. I leave for work early and the triple horn beep is annoying to sleeping kids and neighbors. 

Any help would be appreciated !