radioetcetera has released code to convert Onstar / GMLan bus to plain NMEA data. There is a little bit of work left to be done, but it looks like most of the heavy lifting has been completed. Why would you want to do this?
- GM has put a great external GPS antenna in your car. Why do you need to buy another one?
- It is fun weekend project and a great exhibit of your geek talent
- Using an external GPS should give you much better reception