Not a complete guide, but enough to get you started…
All GM vehicles built since 2007 (and many built before then) are equipped with OnStar modules, which have a built-in GPS receiver. For a long time, various folks have wanted to use that GPS receiver for their own purposes. In older OnStar modules, it was possible to take apart the module and access the GPS receiver’s serial port. This allowed the extraction of GPS information from the module. The downside was that the GPS would no longer work with OnStar. However, if you had a vehicle with OnStar but weren’t subscribing to the service, this was a viable option.
The cost of GPS units has plummeted since OnStar was first introduced. Therefore, hacking the OnStar system to extract GPS information has lost a lot of the appeal. It’s really not worth the time and effort. However, it does seem kind of silly to have a GPS on your car and not be able to use it. So, for those who want to waste their time and effort, read on.
