Hello all,
Sorry to bump an old thread but this seems to be quite a common issue.
I bought a Z4M Roadster yesterday and noticed on the way back from the seller that the sat nav seemed to think it was still at the sellers house.... :roll:
On the way home, I pulled over and put the navigation into diagnostic mode and brought up the hidden menu.
You do this by switching on the ignition, going into the SET menu on the main screen and then holding down the MENU key for 10 seconds. A set of sub menus will appear where you are able to see input from the sensor. In my case, when I looked at the GPS sensor information, it did not have any satellites and the GPS coordinates where not changing as we drove along.
Anyway, having got home and spent some time googling around, it seems that the GPS sensor / GPS antenna failing is quite a common problem on the Z4.
As posted above, for cars with factory fitted navigation, the sensor is located at the top of the windscreen, behind the plastic trim around the location of the interior light.
To investigate, I did not remove the interior light because when I tried to do so, it seemed quite stiff and being a cold day, the plastic trim was quite brittle. Having worked on cars a bit before and knowing the short cut of not removing bits to do a job, hits you much harder in the end, I therefore removed the 4 screws which hold both sunvisors and removed the sunvisors. I then put the roof back a little and you are able to simply slide the middle section of the trim which runs along the top of the windscreen towards the rear of the car and remove it. The two side pieces therefore stay kind of in-situ. You are then able to access the GPS sensor, which you will see is located on a grey metal bracket which is held to the car by two phillips screws.
First of all I tried disconnecting and reconnecting the plug to the GPS sensor. The plug is located about 3 or 4 inches along the wire as it runs towards the left hand A pillar and is simply a pull connection.
When I disconnected and reconnected the GPS sensor, whilst watching the number of satellites within the hidden menu, a few seconds later, I was suddenly able to get reception from 6 or 7 satellites, so it seemed to be a bad connection.
However. . . it then stopped working again. I wiggled the connection and this was not the problem. The problem seemed to be the wire at the location where it goes into the actual sensor itself. If I pushed the wire in, I got reception, if I pulled it a little or bent it down, as it would normally be in the car without me holding it, no reception.
At this point it became obvious that the problem is the sensor itself. It started to look like I would very likely be shelling out for a new GPS sensor. I therefore decided to have a go at fixing the existing one. It was clearly a silly connection issue and if if mine was knackered anyway, what did I have to lose?
I removed the mounting bracket complete with sensor from the car, removed the sensor from the mounting bracket and removed the plastic bracket which holds the sensor to the metal mounting bracket (4 small gold screws). I then was able to carefully prize the sensor open using a small flat blade screwdriver.
Once the sensor was open, 3 small gold screws hold the PCB in the metal sensor housing chassis. The signal wire is soldered onto a metal part of the sensor a few mm after where it comes in. This connection looked a bit ropey so I simply removed some of the solder, re-soldered the connection and tidied it all up.
I put the car back together and it now works perfectly. So, if you have this issue and have used a soldering iron before, have a go before you buy a new sensor.
