I've searched the forums but haven't yet found a solution, hope someone here has suggestions:
2000 M5, MKII Nav with 16:9 display, no TV-tuner or other mods.
Was cleaning the beast with the stereo on. Radio stopped playing and when I tried to start her up: click, click, click. Ok, not quite dead, but marginal battery. Got a jump and all has been fine ever since, except for the blank screen. Radio/CD controls work, screen moves to expose tape player when the button is pressed, the screen's backlight comes on, and no problems getting CD's out of the Nav computer.
Troubleshooting thus far:
1. Based on researching m5board, it seemed most likely that the NAV computer firmware was corrupted due to the battery problem. Note that I was missing one symptom that most folks with Nav computer problems report: radio/CD player shuts off after 3 minutes of play.
2. I downloaded the v27 firmware, burned at 4x to a memorex CD-R, and loaded it. (Used the often quoted http://www.m5board.com/vbulletin/sho...586#post711586
thread, thx drewdwn!) No go, still blank.
3. Dowloaded and loaded firmware v23. Still blank.
4. I should mention that I am doing these loads blind. So I wasn't even sure that they were working, until the next step.
5. I inadvertantly botched a second (or 3rd?) reload of the v23 firmware. I assume that I did something wrong because the stereo began shutting off every 3 minutes.
6. Reloaded the v23 firmware. Radio/CD now plays without turning off after 3 minutes, screen still blank.
7. I pulled the Nav unit and reseated it's two cables, still blank.
8. I now begin pressing buttons. I turn the car on, wait a minute, and press the right knob once; the assumption being that I am accepting the "don't play with my knobs while driving" message. Then I begin repeating the following sequence: menu button, turn knob clockwise one step, press knob. This eventually gets me to the "monitor off" menu option (though I can't see the menu) and the display goes dark.
9. Each time I start the beast I can press the right Nav button twice to make the blank, but backlit, display turn off. This means some component in the Nav system is remembering that the "monitor off" option was selected when the car was turned off.
This is where things stand now. I am stumped.
What controls the menu on the display? Can I assume that the Nav is working because the "monitor off" menu option works?
Can anyone give me some other short sequence of buttons I can press to verify Nav computer operation?
Do I have a bad LCD? Is there a self-test or some of way of testing the display itself?