Hi Everyone. I know im a bit late but I just got the GS3 yesterday. I have a 2011 Expedition with the touch screen Nav from a 2010 Ford F-150. I wanted the touch screen nav system but I wanted the controls on my steering wheel to work with it so I went factory. After a little over an hour, a lot of prayer and a bit of cussing... maybe not in that order... I got it to work. I hope this is able to help other with problems they might be facing. My method was a bit extreme but it did work. Models my differ.
I have to give credit to the person that detail the basic instructions of going to "MAP Profile & TXT Notification". I followed his model and I do believe it kept me in the right direction.
The 1st thing I did was reset my phone to factory. Make sure you back up your txt and contact etc. On your nav system, delete your existing GS3 phone. Then I reset my radio in my SUV. I found the reset under the advanced button under phone setting. Actually, for my model nav system, EVERYTHING was under the advanced button under phone settings. Im not yelling everything to be a butt about the location. Like i said, models are different. I want others to know that have the model I have not to look at the system settings but to go to the phone settings. Ok, back to the reset. choose the "Master Reset" from here. I will say that after every step, cause i wanted to make sure it worked. I did fully power down my truck radio and power it back on. I don't know if it helped but in the end, the TXT works. After the reset is done. I set my accounts back up on my cell phone. Until you are finished with the Nav setup, I would suggest that you don't click the "do not show this again" option on your phone for the notifications that pop up. Reason being, I probably would have been finished a long time ago if that wasn't checked on the message showing that my sync wanted to access my phone's messages. Go figure

After you set your acccounts are back on your phone it fun time. Im also going to make this a little easier to read
Click on Phone (on your Nav System console)
Press Settings
Press Add
Pair your phone (find sync and enter the numbers in)
Make sure to allow everything but don't don't click the check marks not to show this again on your phone
Once phone is paired and connected. look back at your nav console.
go to advanced button under phone settings and make sure Map Profile and text message notification are both on.
If these are both on and you did get a chance to actually read the pop up on your phone and one of them said that sync is trying to access your phone's messages then this should now work for you. To check it. I did a preprogrammed text "Call me" to my own phone using the number pad and typed in my number. After having the phone for a week and basically writing it off as not working, I was happy to receive the text message. Good luck to you all and God Bless.