I have recently brought a Vectra C (2006), I am a first time Vauxhall owner so they are totally new to me, so far the car is great, however I have found that to operate the built in sat nav system you need a CD or DVD for the maps. The car has the factory fitted CD70 Navi system.
After a little internet research I have managed to get hold of a CD that appears to work but I am worried there is a bigger problem with my GPS system somewhere.
The CD I have allows me into the Navi menus, it has loaded the maps and it all looks like that is working fine, but the GPS is yet to find my position, it constantly shows the strike-through GPS icon to indicate no GPS signal.
I have had the Navi on for a number of journeys now as I read that after the car has moved a large distance or been turned off it can take 30 minutes to find your position again, but I have now driven for hours with the Navi on and it still has not found GPS signal.
The maps show and I can input destinations and my vehicle icon moves as I drive, but in the totally incorrect location and obviously it moves across the map without following the roads as if I am cross country driving.
So it seems to have no issue with the map CD, nor the movement around the map, but just can't lock to my location as it can't get GSP signal.

Like I said this is the factory fitting unit, it has had no modifications at all so I am wondering is this a fault in the GPS system or antenna? Or is it something to do with my map CD? To be honest I would be happy to pay the £80 for the latest map CD from Vauxhall but only if that is going to solve my issue, don't really want to buy the CD only to find the GPS still can't lock on and nothing is solved.
Has anyone had any problem like this and solved it themselves before heading to a garage? To be honest I can't even find any diagrams or information on the wiring and GPS system to even know where the antenna is located to check if it is something as simple as not being hooked up for some reason. I have learnt how to get into test mode but all this tells me is I have 0 GPS signal.
I have searched through the forums for GPS issues but have not found a thread about the same problem with the factory fitted unit, only for installing new or aftermarket units.
Any advise is well appreciated. Thank you.