I have an ‘SOS System Limited Functionality‘ error that pops up on my ‘17 HSE (Gas), which looks like is caused by a dead battery in the TCU (Telematics Control Unit).

Any idea where this is located? Any one else have to replace theirs?

It has manual 3rd row seats in case that affects the TCU unit location.

 

My 2017 In Touch subscription just expired and with it I believe the SOS function. Maybe that could be your situation.
I do not have your error, or any error that I know of.

 

Dealing with this exact issue right now. It just popped up on last Friday night after I started the vehicle. I used the GAP tool to check on the exact code and GAP shows mine as rhe battery being bad and needing to replace. The telemetrics unit is located on the left side (drivers -US) c pillar below the seat belt upper mount. If you pull the door seal up along this area and shine a light in there you can see the connections going to it. Now some good news. It is about a 20 minute job to get to with just a 10mm socket and and a small torx bit needed. Bad news. $100 plus for 2 AA sized batteries. Local dealership had it listed for $135 but not in stock. online at places like Lake Bluff LR was from 45 to 60 but most were out or stock or would not ship due to the hazardous material. LR British parts has it listed in ebay for 99. Mine is due in Thursday and I will post some pics of the install if you like. Manufacture date of the bad battery was 8/17 on mine so it was about time it went out.
https://www.ebay.com/itm/36376131913...mis&media=COPY

 

Perfect, thanks so much Donc!!!

I'll get the battery ordered and yes, install pics would be great if you can manage it.

Thanks again!

 

More than happy to. Looks for something Thursday night when I get back from our LR Club meeting.

 

Well got it swapped out late yesterday. Not too bad of a job to do but take your time on it. The only issue I have afterwards is the amber SOS warning is still showing but the codes have not refreshed so that is good news. There is a TSB on this and it states that in some cases the vehicle will need to run at least 1 hour for it to clear. Hopefully that is the case for me and I did not get a bad battery.

TSB : SSM74189 Land Rover Technical Service Bulletin (tsbsearch.com)

Pull the plastic sill cover from the left side rear seat door straight up and use a panel puller to release the plastic tab located under the cover

Size 40 Torq bolt on the cargo tie down will need to be removed. Telematics unit is located behind the rear seat switch bolted to the side of the vehicle.

The metal clips that hold trim to the body will need to be carefully lifted away once the door seal has been pulled.

Hidden panel that needs to be pried up to reveal a 10mm bolt under it. Once release you can move the lower c pilar cover towards the inside of the vehicle to gain access to the unit behind it. EDIT: If you have a cargo cover in place move it out of the way as it will stop the lower pilar cover from being pulled away far enough from the body to gain access.

Telematics unit battery cover removed. Size 10 torq if I remember correctly.

 

Error message and stored codes for reference

 

Just a quick update. The vehicle needed to run for a hour. Error is no longer popping up either on the screen or when checking with the GAP tool.

 

Can you remove the wrap from te old battery to see the type of battery cells (i.e. NiMH ??)
And measure those cells? We can then just build that battery pack and reuse the old connector.

 

what I was thinking as well. Needed to bring my RV home today to get it ready for the Hill Country Rover Rally in 2 weeks. I should have time in a day or 2 to get into the bad battery package and see what's there. I will post pictures of what I find.