Broken navi computer?

[herbie]

I have trouble with my MK IV on a E46 (2001 330i Touring).

The car originally had a MK III, but that was toast when I bought the car (used) and the dealer replaced it with a MK IV. The front end is the mono car radio with tape player and the small mono screen, not the fancy 4:3 or 16:4 screen.

The problem is that the navigation computer is sometimes having trouble with orientation. While standing still in a location not covered by the map, the big arrow that is displayed sometimes suddenly starts turning around as if the car was spinning around. When driving on a road covered by the navigation CD, the navi suddenly tells me I need to turn around or that I'm driving on a non-digitised road, a couple of minutes later it again finds the correct position and then again is lost a couple of minutes later. The antenna cable is correctly connected to the navi computer.

I have to mention that I had trouble with the car battery often running down. The service center did some troubleshooting and they pinpointed the navi computer as the source using too much power and temporary disconnected it. I had no problems with the battery in the timeframe the navi computer was disconnected. I have since reconnected the navi and it seems like it really doesn't stop. If I just sit in the car, closing and locking the door, I can hear the DVD motor on the navi computer running. I waited for 10 minutes and it was still running. How long after locking the car should the navi computer be turned off?

I'm very hesitant to again replace the navi computer as the current one is practically new. Could there be some other component causing trouble? Is something else powered by the power connected to the navi computer (for example is there a antenna booster/amplifier that could have been disconnected when we disconnected the power to the navi computer)?

Also, based on the navigation training manual for the MK III, while in the service menu the Gyro sensor should have values around 2500. On my navi (a MK IV which is not covered by the training manual) the reading is from 800 to 1200. Is this ok? Could somebody with a MK IV please check what the Gyro sensor reads on your car? Go to the Main Menu, then select Set, then hold the Menu button for 8 seconds and you will be in the Service menu. Select "Sensors" and look at the values for the Gyor sensor.

Thanks.