I have a strange problem with my 2005 trailblazer LT with I6 engine. I had battery out for servicing for a few days and today when hooking battery back up it self started. I took the negative cable of and it still ran. I had to step on brake to get it to stop. No key was in the ignition. There is no remote start switch that I know of at least.. I have searched the web and other forums but haven't found a solution to my mysterious defect. please advise.