I have a 2009 H3 with the basic stock H3 radio (single CD, XM). I am getting a stock 2009 H3 GPS system off eBay. I know will need to change the roof top antenna (which I believe is XM and OnStar only), but I was assuming all else would be plug and play.
The dealer told me there is a wiring difference in the H3 - he sez the GPS radio requires a speedometer feed wire that is not part of the stock (non-GPS) radio harness. Really? The dealer did say he had no issue changing the security code so it will work OK. But he said without the spedometer feed, the GPS won't work right. ???
Does anyone have any experience in this area? I gotta believe GM would have a stock harness that was not radio dependent.
Any other issues to watch out for?
Thanks!

 

I've never heard of that before. He has no solution to make it work, or its just that he's trying to charge you extra for the feed wire?

 

Hi its the vss wire the dealer is talking about. The vehicle speed sensor wire, it will work with out it but tracking could be very slow, you will know if it needs it by how it tracks after driving the truck.

 

This VSS was my guess, but I assumed the stock (non-GPS radio) had a VSS as it had some auto sound level adjustment. I thought that adjustment would have come from the vehicle speed.

Dealer said without this wire, the GPS would not display a vehicle on the screen but rather a question mark where the vehicle is supposed to be.

 

my cheap gps tells me my speed,right now!!

why does a gps need vss??

 

The vehicle GPS uses the VSS so when you go into a tunnel - or lose GPS signal, it extrapolates and keeps the navigation sort of accurate.

In the end, I bought a Kenwood in-dash GPS receiver with Garmin GPS from Crutchfield - it is the bomb! Easy to install (no modifications at all), simple wiring, easy to use. The factory GPS was going to need a "Lock Pick" to enable a back up camera, and still didn't do nice things like iPod control. Besides - the after market stuff was way cheaper! Crutchfioeld was great to deal with!

 

i guess ill have to be careful not to get lost in a tunnel!!
wow,most of us never see one