My security light(solid orange) on 2002 GMC Sierra 1500

My sercurity light stays on even after i turn my truck off,it stays on till my battery dies. Iv been told it could be the BCM or my ignition cylinder but im not sure. Its a chipless key and i have no power windows or locks installed. Any ideas?

Asked by for the 2002 GMC Sierra 1500
seek diag from your mech. car needs insp to be sure