Installing a navigation system

[msu90]

Newbie here...I posted this question in the electronics forum but haven't had too many hits.I bought an OEM navigation unit for my Vibe (on eBay) and hooked it up. The navigation system works but the radio and CD player have no sound. I searched the archives and I guess there's been debate whether you can or can't swap units. The hookups all seem the same in the back of both units and I attached the GPS antenna to the back and mounted it under the dash.Anyone have any ideas? The guy I bought the unit from said to take it to the dealer and have them set my computer up to handle the unit. They (the Pontiac dealer) just called and said they can't figure out why it's not working and want to send me to this company that specializes in this stuff about 45 minutes away from me HELP!!!

[ebslopp]

do you have the Moons and Tunes package? I don't know for sure, but the Nav system might require an external amp like the one in the Moons and Tunes package. Maybe someone else knows for sure.

[msu90]

No moons and tunes. In reading the other threads, supposedly if you had the moons and tunes, it could not be done, though one member tried it (had to disconnect his amp) and got it to work. I tried to contact him but haven't heard from him.

[Jahntassa]

The wiring harnesses may be slightly different, I don't know. The NAV system does not have an external amplifier.