I wonder if anyone can point me in the right direction – 98 740il – I have the cd changer and nav unit (old one with cds) – was driving tonight and out of the blue the 4:3 display unit flashes on and off about a dozen times (audio cd was playing) and then goes out, and then audio cuts in and out and then goes out– display would come back on when I hit the clock button but none of the menus or scrolling would work. Now when I turn on the car the display comes on but its locked up except the clock – menus are there but knobs don’t do anything, radio doesn’t work, cd doesn’t work etc… any ideas? As I understand it there are 4 components, the display unit/cassette player in front, the dsp amp, cd changer and nav player in the trunk. Is that correct? The cd changer comes on and loads cds, the nav unit powers on and ejects disks etc… the fuses are good – any help would be appreciated – thanks, Todd

There's 5 parts
The fifth is the radio module.
That could be the issue. I have heard of them going out and causing similar symptoms.
Sorry I don't have more. I'll try and find some links.

Would the radio module being bad cause the entire thing not to work? it turns on when I open the door etc, just cant move the menu or turn on the radio/cd player or go to the nav etc..

Always first thing to try is to disconnect the battery for 10-15 minutes...

Always first thing to try is to disconnect the battery for 10-15 minutes...

agree 100%................. and while waiting around, go to www.e38.org to do some reading

I had already done that - disconnected for about an hour - same thing - if I open the doors the 4:3 screen comes on - turn on the car and the menu comes up but its all dead - cant move the cursor, cant turn on the radio or cd - its like its frozen

Update - I tried unplugging the different modules one at a time to see if I could find the culprit - the end result is if I unplug the Little Trimble unit from the I-Bus, then everything works again - the radio, cd player, the display and computer. I plug the timble back in, it all freezes up again - so currently I have the trimble unplugged - the only artifact I see is that none of the steering wheel controls work now - any ideas??