Nav Unit Replacement
 

Recently picked up this X5 with a stereo issue - screen was busted on the old small screen tape deck, so I picked up a widescreen monitor. Monitor powers on but screen is still blank, and music will play but cuts off after a few minutes. DSP system BTW.

After reading a lot about these systems it seems the next step is to check the nav unit. What's in the car is part #65906908311, MK II according to real OEM. Sounds like the MK IV units are the best, but I really just prefer the most affordable solution at this point. Any way to test or repair the unit myself? Anything else I should check prior to replacing?

Will an MK I work, MK III? Are all of these units interchangeable? There also seem to be numerous part #s for each MK unit, will all work with this system or only a select few?

Check ebay. I have seen MKII navs at around $200. What do you mean that by the monitor powers on? How do you know?

Yeah I've been scouring eBay, there are some for $100. I just wanted to confirm other part numbers would work, even though they are also MKII. I can see the screen come on - its not showing the proper display but its not the same black either. Also the screen tilts. What I meant to indicate by this is that I don't think it's a fuse for that unit.

Forget about MK1 - stick to MK2,3 or 4... the image on the screen is created by the Nav computer or by the TV module. Neither have anything to do with the sound of the system, the sound is controlled by the BM53 radio that is stuck next to the battery. the radio has its own 10A fuse inside the big square connector, the Nav unit should have its own fuse on the backside of it - i am not sure about the fuse there, i remember the CD changer has its own personal fuse on the back of the unit...

those are in addition to the fuses in the right side of the trunk - is it safe to assume that you have CHECKED all those fuses with a multimeter, and not just visually???

Replaced fuses and tested for good measure. Sound came on tonight after fiddling with HU. No fuses I could find on back or near Nav unit, so went ahead and ordered new one. Will report back with results.