Onstar antenna with GPS Nav?

[Klaus]

OnStar is comprised of 2 systems, Cellular Phone Service, and GPS. Therefore, the OnStar antenna supports both. As a matter of fact (if equipped with XM Radio), the 2005s OnStar antenna performs 3 functions - OnStar Cellular, OnStar GPS, and XM Radio.

I REMOVED OnStar from my truck, so I had the option to use the OnStar's GPS for my NAV unit. You CANNOT use the antenna for both OnStar GPS and NAV at the same time.

Now - The NAV unit's antenna connection is non-standard. Therefore, what I did was to cut off the coax from a NAV GPS antenna and added the MCX connector to it. That gave me a patch cable to connect the NAV unit to the OnStar antenna cable.

Most folks should just install the regular NAV GPS antenna cable in the dash and be done with it. 2005 owners MIGHT have the option to replace both the OnStar antenna and the complete roof wiring harness to get the tri-band OnStar antenna mounted. I didn't do this as my 2003 had different connectors under the dash.