Hello,

I am going to install a 2 way radio in my truck and it needs a GPS. Before I drill a hole and install a dedicated GPS I wonder if anyone has circuit diagrams or know if there is a way to tap into the onboard GPS that is part of OnStar?

Thanks, Louis

I believe you can only tap into onstar on the 02 and older trucks.

Hello,

I am going to install a 2 way radio in my truck and it needs a GPS. Before I drill a hole and install a dedicated GPS I wonder if anyone has circuit diagrams or know if there is a way to tap into the onboard GPS that is part of OnStar?

Thanks, Louis

Check out this site... I found it a while back but haven't dug around it much lately... It involves hooking up a computer and setting the GPS in the onstar unit to NMEA mode. Basically you can't have both the feed and the Onstar working at the same time...

http://members.cox.net/onstar/

Doug

I believe you can only tap into onstar on the 02 and older trucks.

This is correct. In the 02 and earlier trucks the On$tar unit used a Motorola GPS module that sent its data out over a serial interface. It isn't sent in NEMA format, but a command can be sent to the module to switch it to use NEMA format. Starting in 03 a single-chip GPS receiver is integrated onto the On$tar board. Communication is over some sort of parallel data bus.