I just purchased the Delphi Vehicle Diagnostic Tool and must say I am quite impressed. http://www.verizonwi...iagnostics.html Out here in Arizona we have scorching temperatures in the summer and the ability to start my 2008 Sierra from virtually anywhere is going to be a life saver. This is the main reason I purchased this device. It consists of an OBD-II module you plug into said port. It connects to Verizon's 1G network which is almost everywhere. It then communicates to your smart phone over the cellular network. I can remotely start my Sierra while leaving a movie theater, restaurant, etc. It also provide Geo tracking, engine codes, Geo fences fuel level, battery voltage and many other features. The details Price $250 $5 Monthly for 1g access to Verizon I had to get rid of my unlimited plan and switch to a Share Everything Plan in order to activate. I know this will be a deal breaker for a lot of people but I am near wi-fi over 95% of the time these days. My data usage has gone from 4GB per month to .1GB per month as a result. YMMV.