Originally Posted by GCoop

Hello all,

I have read this thread with great interest as I have been helping my neighbor with his flaky MKIII Nav computer in he E39. His issue seems very similar to the one(s) described here and I was hoping to get some advice on what to try next.

The Short Story: Neighbor left his car running--Car runs out of gas and quits--battery goes dead from key still in ON position before owner realizes what happened.

The only thing left to sort out from this mishap is what brings me here. As you already have guessed the MKIII nav computer is the issue. Here is the description of what I have seen happening with my neighbors car and need the Guru's here to help me narrow down where the problem is and what my next steps should be in troubleshooting this for my neighbor. I do not have Nav on my E46 but my neighbor sees me doing all sorts of things to my BMW and considers me an expert in BMW land. I just want to save him a few hunders dollars if at all possible.





Description of Problem:

• MKIII nav with the widescreen monitor in the dash screen goes blank shortly after is starts. All other functions work properly. Radio, cd, tape, etc just cant see anything on the screen.
• Upon powering the nav (either by turning key on or opening trunk/pressing eject button once) I see the red light on the nav computer come on solid, disc spins, red light blinks then goes out after a while, then this whole process starts again. My description would be that it seems to be continuously rebooting.
• On the monitor screen while this is happening I ALWAYS see the ====BMW==== logo and sometimes get as far as the [Accept] screen. before the screen goes blank.
• If we are fast enough before the next 'reboot' we can press the button to accept and get to the next screen. Never enough time to get any farther.

What I have tried/havent tried:

• I have tried removing the disc and that does not change anything. Behavior is the same.
• I have unplugged the nav computer completely making sure all wiring connections are secure and that did not change anything. Behavior is the same.
• I have not tried holding down the eject button to see if that makes a difference SO this is next on my list of things to try.
• I have not tried to hook my DIS/GT1 Laptop up to his car to see if there is anyhting to see. Unsure of even what to try other than look for obvious errors pertaining to the Nav computer.
• I have not tried to make a firmware CD and try to load firmware. Unsure of whether that is even an option considering its current behavior. Didnt want to make matters worse.
• I have not opened up the enclosure to look for any corrosion/water damage.

Questions for the gurus:



Given my description(s)

• How likely is it that the flash/boot rom chips are corrupt?
• If the boot rom is not likely corrupted what is the next likely cause of this behavior and what to try next.
• What stage in the whole startup process is the unit getting to? If I knew what the process was I that would help me to better pinpoint where the trouble is I would think.
• If holding the eject button down changes the behavior by preventing the NAV module from rebooting like someone else posted--What does that mean? Where should I go from from there?

Any help/insight would be greatly appreciated!