iBus problem driving me nuts! 8 months, still not fixed

[ElectroDan]

I'm really hoping someone might be able to point in the right direction of what to try next. Ever since buying my 2004 4.8iS 8 months ago, I've had a frustrating intermittent problem of my dash lights not working, until I either unplug the LCM or battery.


I thought I'd tracked this down to the stereo, as if I left it off, the problem didn't re-occur. I have the large screen NAV headunit and DSP. If I do use the stereo, the dash lights would go off around once a week. I had to unplug the LCM to reset the iBus system and temporarily fix the issue, else the battery would slowly drain.



So, to troubleshoot I tried the following:


1) Bought another used large Nav screen headunit. Same problem happened.
2) Bought another used DVD Nav unit for the rear. Same problem happened.
3) Bought another used LCM, coded it with my VIN and mileage and fitted that. Same problem happened.
4) Unplugged the CD-autochanger and fitted a BlueMusic adapter in place of the autochanger to stream music from my phone to. Same problem happened.
5) Unplugged the BlueMusic adapter and listened just to radio. Same problem happened.


For a while I decided to just sit my mobile on the dash, and listen to music straight from that. Not ideal, but at least my dash lights kept working.


I was then testing out a Bluetooth OBD adapter to send stats to my phone as I drove. Low and behold, my dash lights stopped working the 2nd day of doing so! So perhaps not stereo related after all?


I then carried on for a while, stereo off, not touching the OBD port, and all was well. I think one day I opened the sunroof whilst driving and the dash lights stopped, so I'm well and truly confused as to what the heck is going on. I know the rear part of the sunroof was modified by the previous owner so that it doesn't tilt up, to prevent a common part from breaking?


The last step I took, was to fit an Android headunit with Resler iBus module. Both large NAV screen headunits I've tried always had a flicker, so I thought perhaps the cabling was damaged and causing the issue. But, even with the 6 metre cable to the rear in place, the dash lights have stopped working, so it's not the cable from the BM54 to the front (I think).


I'm at a loss what to try next. Should I unplug the factory radio? The DSP amp?


Is there anything else on the iBus network that could be faulty that I can somehow isolate (perhaps by pulling a fuse) to see if everything behaves when listening the new Android headunit?


Any help much appreciated!