no crank no start-accessories all work, but no communication with ecu

Hello, if the security light is flashing, then there is a communication concern with the anti-theft system and the key - with the Sentry Remote Key Entry Module. Is there a key that has not been programmed to the vehicle being used? Try a different key perhaps? "No communication with eco" - what does this mean? You cannot perform any testing to determine fault? The data link has a related fuse that could be blown; check fuses. https://repairpal.com/auto-repair-near-me