I have a 2004 with Nav. When you go to the GPS info on the menu, 90 % of the time it shows only 1 or 2 satellites received. However, it appears the nav works OK. Also, the clock is set for auto update (which I assume it gets from the GPS), and is always 2-3 minutes behind. Does anybody know if this behavior is normal?
Are you out in the open or between tall buildings in a city? GPS reception is line of sight. It can be blocked by tall trees, buildings, hills, and highway overpasses.
Is it a factory installed Nav, or was it retrofitted later? I found that a gps antenna installed without a backplane caused these exact symptoms. Once I installed the factory gps antenna, with it's proper mounting bracket (RF Backplane), in the factory location above the instrument panel, it now picks up 6 to 8 satellites.
Is it a factory installed Nav, or was it retrofitted later?
It is factory installed, DVD-based maps. It appears to work right, though sometimes it is off by a little. I guess factory installed navs are also connected to the drivetrain, so it knows your speed in tunnels, etc. It happens out in the open also, not just around buildings, etc. If I watch the satellite screen every so often it will pick up more, but for the most part, when I watch the info screen, it is only picking up one or two.
I am taking it in next week and wanted to know if this a problem that needs fixed, or is it normal?
If it was only picking up one it wouldn't be able to give you speed or position. Two would be way off on position, but may work to some degree. It takes three to give your exact position and accurate speed.
It won't lock on and give you a 2d position (lat/lon) until 3 satellites are located, at least temporarily. It also uses the VSS (Vehicle Speed Sensor) signal to get speed, so it will still show you moving on a map. This is why it works in tunnels.
While buying a 12 channel portable receiver sounds great, you only need to be locked onto four satellites for a 3D position fix (with altitude). The new 24 channel receivers are totally hype and not worth paying a dime extra for. There are only 12 visible GPS satellites at any given time, assuming best-case horizon to horizon visibility (on the ocean). Even using our rooftop antenna in our GPS lab, we've never seen more than 10 at once. Typical is more like 6 to 8.
If it is a problem, I'd suspect the antenna, or the connecting wire (built in to the antenna). Get the dealer to look at it, if it's under warranty. If not, just go get a new factory antenna (with the attached ground plane mounting bracket) for about $40 and swap them. Cheaper than buying a new Nav and finding out it was an antenna connection all along.
Don't know it it's "normal" or not, but it's exactly the way my stock '06 behaves. The position is always good, and the clock keeps time well enough on it's own, so I stopped thinking about it.
Re: Nav Reception/Clock Question 
