I have a TCU (P/N) 84116946993 SW ver 27, HW ver 35 and I am putting in my '03 E39 with Mark IV NAV.

I installed the unit and was able to get it to pair with my phone and work without problems, however, every now and then the TCU takes over and hangs the NAV unit with an indication that BMW Assist is not active. This also keeps the radio from working as well. This activity takes about 15 minutes for it to clear. This action happens randomly, I have not been able to determine if there is a given cycle for this.

I have tried to pull the phone module ribbon connector inside the TCU, however, no change.

Is there a solution for this issue? I did some research and there may be an issue with the firmware in this module?

Any suggestions would be appreciated.