Quote: Originally Posted by openminds
Why couldn't you accomplish it with the 03 Sierra? Does it have a Sony board? If so, the pinouts are the same. Just need to track down either the Sony Software to configure it, or a Mapping Software that will read the Sony Binary output.
Firend did get it up on the Sony board, we are now trying to figure out the later. (Software, etc.)
From what I've read they've changed the Onstar module considerably and the GPS module is now incorporated into the main board. There was a guy that tried to do it on an '03 Silverado and couldn't find any of the points to tap into. I tried to find the thread over at this forum
http://www.aimoo.com/forum/freeboard.cfm?id=421724
but I couldn't find it any longer. His name is Wayne Dohnal and he did a very extensive job of trying to get it to work, but threw in the towel in the end. Here's a little bit of explanation from another thread I did find:
From the pictures this board is the same or very close to the cell phone board from my 2003 Sierra's OnStar box. Just for comparison, the label on my box carries the Motorola logo, "Assy Part No: 15184769", and "Base Part No: 15184770". I believe that the GPS receiver is a custom chip integrated onto the mainboard. I spent several hours searching for a serial data stream and I found two of them, but they are not the fixed bit-rate serial data that we would need. It looks more like a 2-wire signal to me, perhaps I2C or something similar. After a couple of days of getting nowhere I decided that we have been screwed by GM with a new, untappable design. I wish that somebody from GM or Motorola could post some real inside information here for us.
I finally bought an Oncore receiver off of eBay and put it in a small metal box along with the connectors, a backup battery, and voltage regulator. The GPS antenna on the truck works fine with it, but finding one of the mating MCX connectors was another royal pain.