I have a problem that I cannot diagnosis on my 2016 XJL 6L. The car runs fine but any advice regarding this nuisance message would be appreciated.

The charging system fault appears in the message center 10 seconds after the car is started. It allows me to select OK and clear the message, but the fault triangle symbol remains lit when driving.
This has been going on for approx 6 months. The car doesn't get a lot of miles and every couple of months I get the low battery message and use my CTEK.
I don't have SDD and there are no relevant codes when using my Foxwell NT530. I have studied this X152 thread and the 2014 Service Manual.
I checked the battery and charging system. Battery is 12.7v static, 13.2 volts at idle, and 14.4 at 2k RPM under a load. I have a good Fluke meter, CTEK charger, and INNOVA 3150RS OBD scanner.
The Stop-Start has quit working. I tried disconnecting the battery and shorting the two battery cables after ten minutes. I also tried running with the Battery Monitor Module disconnected from the negative terminal, but the behavior didn't change.
I have seen other comments regarding battery charging messages if the battery module is disconnected, but I couldn't verify alternative fault behavior. I have also read Brutal's advice to reset the ECU memory, and Nedoerr didn't disclose his brand of scanner.
So, I assume it is either the Battery Module, the Gateway Module, or a permanent BMS DTC fault that just needs to be cleared.
I can't find where the gateway is located, but see a black box with a single interface listed on ebay under different names (Captive Control/Gateway Control), but not for a 2016.
A similar Battery Management Module is used on many Fords. My friend's F150 uses the same connector. Are these a common replacement item? Does a BMM failure disable the Stop-Start?
There is not a lot of information for diagnosing the Stop-Start on the forum beyond battery maintenance. Is there another test I can run, or is my only option to find an Indie with an SDD?
and sorry for the long winded explanation.....

 

Just one though: Does your vehicle have dual battery configuration? If yes, then it might be that the 2nd battery have been failed.

 

No second battery on a 2016.
Has anyone ever replaced a Battery Monitor Module, or had one diagnosed as bad during dealer maintenance or battery replacement?

 

Without further diagnosis this will be difficult?
I think you need to get the car hooked up to SDD and do a deeper scan.

I would stop messing with the battery monitor stuff that can cause further problems. Be glad the SS quit working! Mine did and it's WAY better!
You did not state if the battery or alternator has been replaced?
Not sure if they need to be replaced but the repair history of the car can sometimes give additional clues.

With a BMS it helps to understand that you will no longer have static numbers like you post? It manages the battery and that include regularly discharging the battery and then recharging it. So the voltage will jump around a LOT more than the old systems that don't use a BMS. If you read Jaguar shop manuals they recommend that the BMS be reset using SDD whenever a new battery is installed. But then they admit that this is NOT required because the system will self calibrate on regular intervals regardless if the battery has been changed or not.
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