GPS Problem with factory fitted CD70 NAVI unit

[Keeti]

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.

[pecky]

It does sound like an aerial issue to me.

Being an older car I wonder if someone has taken the radio out at any time and not connected the blue wire back onto the radio.

You can get a cheap "Fakra GPS Aerial" from ebay and fit that. It's what the retrofitters use and costs around £8-£10 rather than the expense and hassle of replacing the whole roof aerial and wire.

[soulman]

A lot of people use the cd70 navi to replace the cd30. They tend to use the cheap ebay GPS aerials which are troublesome to say the least. I've tried them on a few vauxhalls now and wouldnt recommend them, stick to OEM aerial...

You can tell if the car has the OEM GPS antenna as it will be a big chunky unit. Post a picture if you can. Another clue is if you remove the radio and check to see what you have on the blue connector.. If its a right angled fitting then it should be OEM lead, if the cable coming away from it is 'straight on' then its a cheap ebay GPS unit..

OEM cabling goes from there to the righthand side kick panel (by the bonnet release, needs two T20 screws removed to get to the wiring). The cabling for the aerial sits in the middle of the big plug which can be seperated by gently pulling the big lever handle down... It then goes from the up the righthand side A pillar along to the rear of the car... About 6-8 inches from the aerial coming through the roof is a big connector which contains the 3 smaller aerial cables.. Normally GPS, FM, phone (GPS replaced by DAB if fitted)

Hope this helps

[Keeti]

I do suspect the problem lies in the roof part to be honest, which looks the biggest pain getting into so I am going to have a go at removing the CD70 unit and looking at the wires in the back, I will probably find the aerial is plugged in there but you never know. So the easiest thing is going to be getting a cheapy Fakra, I would always prefer going down the OEM path but to be honest I really can't justify the cost of this one just to get the sat nav to work. Thank you both for the advice.

[soulman]

Aerial mast and cabling your probably looking at about £25-£30, was you expecting more?

[pecky]

Aerial mast and cabling your probably looking at about £25-£30, was you expecting more?

From a breakers maybe. from vauxhall, the aerial wire is around £35, base is around £50 and mast £20, at least the Astra ones were when I had to buy one.

[soulman]

Yeah, stealer prices are astronomical... Thats why you dont see many people replacing the aerial base once the rubber starts to perish

[manevni0]

And one more thing - did you checked if there are any satellites visible?

You can do this with entering secret menu:

Press "Settings" for 10 sec > "Testmode switched on" will appear on screen > Press "Main" > Press "Navi" button

You will see testmode screen for Navigation.

Looks like this:

http://filolog.uni.lodz.pl/zkp/testmode/navi-1.jpg

In the upper right corner you will see T[number] / V[number]. On this picture T10/V12.

"T" - is showing how many satellites you are connected to;
"V" - is showing how many satellites are visible;

Normally "V" has values like 7 - 10 satellites visible.

[manevni0]

Actually you should press "Navi" button twice in order to see this screen.

[Keeti]

I took the unit out and seems the wire is plugged in as it should be:





And yes I've checked the number of satellites, it never picks up a single one at any time:



My last hope I think is going to be a battery disconnect to see if the modules reset and it jumps into life after, but if that doesn't work I suspect the roof aerial is the culprit. Fixing this isn't something I would attempt myself as I am cack-handed at anything even half easy to do, I would pay for the work so would expect it to be quite a lot so doubt I will get it done right now, might just try the fakra as a cheaper or easier solution for now.