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drawson · 11-09-2006, 08:55 AM

OnStar has 2 antennas. The one on the glass is for cell phone. There is another, usually under the rear deck for the GPS. The cell phone antenna cannot be used for the GPS. GPS requires a circular polarized amplified antenna. I have hacked my OnStar GPS and can get the serial data stream to a PC. Works with most mapping software. Look at the side of the OnStar box. In my Grand Prix there are 2 boxes. One small with rounded edges, This is the cell unit. The other big square one has an odd wire - looks like a piece of black tubing. This for the GPS antenna. There are instructions on how to get into it on the web. Motorola has software for the module, you must switch it from Binary mode to Text mode to work with a PC. Also you need to add an IC to change levels to RS232 for the PC. Works cool with my Car PC. OnStar indicator will go red as it needs Binary mode and gets upset at tex mode.

11-09-2006, 08:55 AM	#18
drawson Newbie Join Date: Dec 2005 Posts: 6	GPS Hack OnStar has 2 antennas. The one on the glass is for cell phone. There is another, usually under the rear deck for the GPS. The cell phone antenna cannot be used for the GPS. GPS requires a circular polarized amplified antenna. I have hacked my OnStar GPS and can get the serial data stream to a PC. Works with most mapping software. Look at the side of the OnStar box. In my Grand Prix there are 2 boxes. One small with rounded edges, This is the cell unit. The other big square one has an odd wire - looks like a piece of black tubing. This for the GPS antenna. There are instructions on how to get into it on the web. Motorola has software for the module, you must switch it from Binary mode to Text mode to work with a PC. Also you need to add an IC to change levels to RS232 for the PC. Works cool with my Car PC. OnStar indicator will go red as it needs Binary mode and gets upset at tex mode.