Hacking the OnStar GPS v2

[Andy] has provided us with his new guide to hacking the OnStar GPS. Previously, we have covered a way to grab the GPS data from an unused OnStar system, however in recent years GM has added much more complex systems, which make it harder than swapping out a serial line. For the new version, [Andy] has figured out GM’s Controller Area Network (CAN), which they call GMLAN. He has also done most of the software snooping and sleuthing, and has mostly solved GMLAN’s method of announcing GPS data. There is sample code available to convert this information into generic latitude and longitude.

Unfortunately for the project, (and very fortunately for [Andy]), he has a child on the way and new job responsibilities, so he is offering up his results to the HaD community to finish up, double check, and provide a good how-to for everyone else. To anyone who decides to pick up this project and run with it, let us know!