MKIV Problem: "Ant Open"

[herrubermensch]

I'm an interloper from the M5Board.com with a 2001 E39 M5 with an MKIV unit that I installed about six months ago and that I bought from a seller on eBay. Worked beautifully and seamlessly until I removed it to install a new stereo. It was out of the car for six weeks. I reinstalled it, and everything seemed to work fine at first, but the NAV slowly but surely was "off" a road or two from where it should have been. A week later, it was a couple of cities wrong--about 300 miles off. I went into service mode, and the almanac has not been downloaded and no reception from satellites and the message "ant open." Now, I know from this board that that means a problem with the antenna or the connecting cable, so I replace both. Same problem.

Is there anything I can do here short of replacing the entire MKIV unit? Any "reset" technique that might cause it to recognize the antenna and download the almanac? Anything else to try before I blow $6-700 on another MKIV unit off eBay? I appreciate any help you can provide. Thanks.

--Peter

[herrubermensch]

Some have referred to "enabling" almanac mode? Is this an approach? How does one do it?

[Roy in GA]

Maybe it's the GPS card in the Nav. They can be replaced. I have helped do it for a MKIII. Not sure it's the same card in a MKIV, but expect so. Do a search on bimmerboard.com nav forum and also here as it's been discussed recently. Jochen may have more info also.

[KiwiJochen]

Originally Posted by herrubermensch

the almanac has not been downloaded and no reception from satellites and the message "ant open." Now, I know from this board that that means a problem with the antenna or the connecting cable, so I replace both. Same problem.

Check the integrity of the antenna connector - make sure the centre pin is OK.

If repalcing the antenna and the cable did not solve the issue then the only thing left is the GPS receive module inside the nav computer.

You can replace the GPS receiver module easily.

New GPS receivers can be bought here:
Navigatie-onderdelen.nl | Navigation par - GPS

[KiwiJochen]

Originally Posted by herrubermensch

Some have referred to "enabling" almanac mode? Is this an approach? How does one do it?

The almanac is the table of satellite orbital data corrections.
It is automatically downloaded from the satellite.

It cannot be "enabled", "switched on" or "switched off". It is simply there.

On a working system, the almanac is lost when the car battery is disconnected. The car then needs to re-acquire the almanac, which can take around 10min on a stationary vehicle, or up to 30min when moving.

Having almanac loaded means the GPS acquires satellite signals much faster at switch on.

[herrubermensch]

Originally Posted by KiwiJochen

Check the integrity of the antenna connector - make sure the centre pin is OK.

If repalcing the antenna and the cable did not solve the issue then the only thing left is the GPS receive module inside the nav computer.

You can replace the GPS receiver module easily.

New GPS receivers can be bought here:
Navigatie-onderdelen.nl | Navigation par - GPS

Thanks very much. I will check the center pin. Is it on the unit itself or in the cable? If in the unit, what if it is damaged? What is my remedy? Can the antenna connector itself be replaced?

[KiwiJochen]

Originally Posted by herrubermensch

Thanks very much. I will check the center pin. Is it on the unit itself or in the cable? If in the unit, what if it is damaged? What is my remedy? Can the antenna connector itself be replaced?

The cable has a female centre pin that is reasonably robust

The connector on the nav is more fragile, and sometimes gets broken / bent. Be careful checking it!

It is possible to purchase replacement SMB right-angle panel-mount gold-plated connectors - but replacing it requires proper tools and soldering skills. So if the connector is damaged, you may be better off replacing the GPS receiver module.

See here for parts:
Navigatie-onderdelen.nl | Navigation par - GPS

[herrubermensch]

Originally Posted by KiwiJochen

The cable has a female centre pin that is reasonably robust

The connector on the nav is more fragile, and sometimes gets broken / bent. Be careful checking it!

It is possible to purchase replacement SMB right-angle panel-mount gold-plated connectors - but replacing it requires proper tools and soldering skills. So if the connector is damaged, you may be better off replacing the GPS receiver module.

See here for parts:
Navigatie-onderdelen.nl | Navigation par - GPS

Thanks so very much! I've ordered the connector and will try soldering it in. If that fails, I will order the new GPS unit and replace it altogether. Thanks again!

[Roy in GA]

Another supplier of the GPS. eBay Motors: BMW TRIMBLE GPS MODULE LASSEN SK-II WITH ANTENNA (item 280324690441 end time Apr-18-09 15:03:38 PDT)

[herrubermensch]

Update: I was unsuccessful at soldering in the replacement antenna connector, so instead bought a couple of Trimble units off eBayfor $50 bucks. Installed one, and MKIV is ALIVE again! Thanks so much for the guidance, here. Saved me a lot of money!

--Peter