Hi ,exactly what is the purpose of this light.I've only owned this Jimmy for a few weeks and never noticed this before.This vehicle has electric locks and mirrors not remote entry as far as I know.What is the security lights purpose and why is it flashing Thanks Alan

 

Your truck likely has the CTD (content theft deterrent) system. Have a read through the post linked to below:
Content & Vehicle Theft Deterrent Information

And you might want to look at your RPO codes to be sure that you do not have remote keyless entry. AU0 is the stock RPO code for RKE.