SOS error diagnosing (after battery disconnect)

[acarpenter86]

2011 35d X5
Two questions…
1. Found the plug (see photo) near rearward fuse box. Is this “delivery” plug that is now unused?

2. I found item in question because I’m trying to solve my SOS and no Bluetooth error.
Last summer when I bought the e70, the PO had bypassed the TEL/MOST module so the radio would work, but I always got “SOS” malfunction.
In the middle of a road trip, I started tinkering and plugged in the optical cable and amazingly BT started working and no more errors.
It was fine until last week I was hauling something and had to borrow the e70’s battery… well the silly SOS message came back and no audio. Back to using the MOST bypass for radio but I get SOS and no BT.

I’ve tried TWO additional MOST modules I sourced locally and no dice. I’m wondering if it’s not getting power. I’m missing my fuse card so that’s a problem, but I checked all the 5V and all good.

I will say, previously before I got it to work “magically” the BT items would show up in iDrive but would not connect when trying to pair. I assume because the module was getting power and then when I plugged the optical cable in that completed the circuit and bam, Bluetooth worked. Right now, I just get a “please wait” message if I go to telephone. Therefore I think the module is getting no power.

Theories:
-I unplugged the battery and blew a fuse that I cannot find during that process.
-when I unplugged the battery, I entered some power save mode and the management system stopped sending power.
-this e70 is cursed and should be sold (jk)

By the way I did try using ISTA to disable “transport mode” but nothing changed.
The module shows “no communication” in ISTA.

Thanks for reading the novel… any help MUCH appreciated. Such as, what fuse, what wires on the MOST module supply power.

[RL18]

Remove the rear trunk drivers side panel and check for water damage. The telecommunications unit is in there. Seems to be related to the issues your having. I had a clogged roof drain and was collecting water in the little cubby and it was splashing on the connector shorting mine out.

[acarpenter86]

Originally Posted by RL18

Remove the rear trunk drivers side panel and check for water damage. The telecommunications unit is in there. Seems to be related to the issues your having. I had a clogged roof drain and was collecting water in the little cubby and it was splashing on the connector shorting mine out.

Thanks for the comment, but not water ingress detected.
I also swapped in two different TCU modules, so I think it is most likely a power issue... makes sense because it stopped working after I borrowed my e70 battery.

[jbash87]

Do you have a voltmeter? You should check to make sure the TCU is getting power or not at the TCU plug.