My 2016 F Type R Coupe has been suffering from the "SOS Limited Functionality" warning for several months. I finally got around to replacing the TCU battery today and thought I would give a quick overview of the process for anyone else that wants to do the same.

I started by purchasing a
Replacing the battery is very straightforward and only requires one or two tools (depending on your particular vehicle's build). Here are the step-by-step instructions:

1) Find the cover located between the seats, above the center console


2) Gently pull forward on both sides at the top of the cover to release the clips, then lift up and remove the cover. This will expose the TCU:

3) The TCU battery is located behind a cover panel held in place by a single T10 (Torx) screw. Undo this screw and remove the cover to access the battery. If your car is like mine and the cover is blocked by the metal cross-car bracket, move to Step 4. Otherwise, you can jump to Step 5.

4) On my car, the large metal bracket seen in the above photo prevented me from being able to remove the battery cover. I had to loosen the three 10mm nuts holding the TCU in place so I could lift it slightly and then remove the battery cover. There are two nuts on the (US) driver's side of the TCU and one on the passenger side (hidden behind a bundle of wires which needed to be pushed out of the way for access). I used a deep well 10mm socket to access all three nuts.


5) With the access door removed, I used a pair of needle nose pliers to gently pinch the plastic latch on the battery connector and remove the connector and battery from the TCU. The connector and latch are visible below. (Unfortunately, I failed to get a photo of this step).

6) After removing the original battery, simply install the new battery (being careful to make sure the connector is correctly oriented with the latching clip toward the passenger side of the car) and reverse the previous steps.

So far, the new battery appears to have remedied the SOS Functionality warnings on my car. This is an easy repair for anyone suffering from the same issue. I have seen some other threads that indicate the warning message could also be related to an issue with the actual TCU module or the roof antenna, but I decided to start with a replacement battery and hope for the best. So far, so good.

 

Thanks for the write up, my 2015 does not have a module in that area and I’m not receiving any error message either.

 

Good job! Been getting that stupid error on and off for months....was never sure which batt to get....just ordered the last one on Amazon! Thanks for the link.

 

There's another thread on this that includes information on the battery pack itself. I promised pictures of the replacement operation but never did, so thanks for this.

https://www.jaguarforums.com/forum/f...nality-191247/

I got the information on the two batteries and someone else was able to source them and make a new pack. The two cells are both lithium but different flavors. One is rechargeable and the other not.

 

Thank you for the great photos and writeup. I'm not having any issues currently, but with a MY2017, who knows what may be coming. I do have a question, if you could clarify the process for accessing the battery pack. You write that there is (or may be) a metal cross bracket that blocks access to the small battery cover. In your photos, it doesn't look like that cover is blocked by the bracket (3rd photo) . Is there more to the battery cover than the photo shows?

 

The photo below should better illustrate the issue I had removing the battery access door. In my case, the silver metal bracket overlapped the bottom of the access door just enough to prevent removal. The yellow line highlights the interference:



The door is held in place by a single Torx bolt on the left and two tabs that tuck into the case on the right. With the bolt loose, you should be able to just rotate the door forward and remove it. My guess is that the parts were designed such that the access door should be above the top of that bracket for easy removal. In my car's case, either the TCU is a little low or the bracket is a little high (or both) and there was interference. What should have been a 5 minute job turned into 10 minutes due to the need for a few more tools to loosen the TCU and lift it slightly to get the access door over the bracket.

 

I broke a trimpiece on one of the door panels, so was a bit hesitant to pull on the console section. No worries!! Came forward and up as described. Inside it is identical to your photos. Thank you again for posting this. I feel totally comfortable following your directions for the battery replacement.

 

I want to follow up on my initial post to add one more step to the process - Reset the TCU once the battery has been changed. The SOS Limited error messages will not automatically go away as the vehicle does not automatically register the replaced battery. You will have to open the cover to the maintenance assistance button located on the LHS (driver's side USA) of the SOS button panel. I pressed on the top of the button cover to drop it and expose the button for maintenance assistance.

The clear square in the center of that area is the reset button.

Turn on vehicle accessories by pressing the start button without pressing the brake pedal.

Press and Hold the maintenance assistance button. It will begin blinking somewhat rapidly in an amber light. Hold the button until it starts to blink slowly. release the button and turn accessories/car off. Wait 5-10 minutes for the Telematics System to run a self-diagnostics and register the new battery and voltage level.

Once I completed this last step, my SOS Limited warnings have been greatly reduced. I still get the occasional warning message, but they are much less frequent than before replacing the battery and performing the reset procedure.

 

I suspect it takes a few drives to fully charge the replacement battery - my new one was only 3.7V when I took it out of the box, the old one I removed was over 4V.

 

Good info thanks!

 

I did not do the Telematics reset because I didn't know about it. The "a few drives to fully charge the replacement" method did work for me, so the reset must not be entirely necessary, although I would probably have had fewer drives after replacement with the annoying warning.

 

Been thinking about proactively replacing this as my 2017 was built late 2016. Was not getting any SOS messages, but I believe the Jaguar Remote program communicates with this car via that telematics unit. Thank you GearHead01 again, for excellent photos and write up.

Here are my notes:
1. console cover comes off as easy as described in original post.
2. I did have to loosen the three nuts to juggle the telematics unit to remove the little panel door.
3. only the lower left nut was easy to access with socket.
4. the upper right stud requires a 10mm DEEP well, ok, easy when you have that socket. I didn't so I had to improvise.
5. lower right was a PITA. A shorty 10mm wrench was the only thing I could get on that nut as in this car the nut was partially behind that silver horizontal bracket.
6. My first ordered battery from Amazon did not come as in the product description's photo. The label looked fake and there was no battery production date on it as there was in the product photo. I sent that one back. Looked at another JLR part number battery. That one also showed a label with the battery production date on it, so I ordered that one. It also came with the JLR part number label that looked like it was printed off my household printer. Sigh. So I figured that that must be how they are sending the batteries. The battery was the same "Tadiran" manufacturer label as the one in the original post. So I gave it a try.
7. I have an active Jaguar Remote account on my tablet so I fired that up to see if it could tell me where the car was. Yes. good there. Then I tried the lock/unlock and flash/beep options. Both those worked as well.
8. Since I didn't have an SOS message, I did not press the reset button as later described in the post. At this point, it appears that there is sufficient power in the new battery.
9. The factory original battery that I removed was dated November 2015, so almost a 10 year old battery.

Will check everything again after I drive the car the next time.

10. Drove the car today, a good 20 miles, some in town roads, some interstate. No messages, no warnings.

 

Question regarding the TCU battery and possible symptoms a dead battery could cause. If the battery were dead, could it cause an interruption in the MOST network continuity? The symptoms I've been troubleshooting include:

Radio is inoperable.
Navigation is inoperable.
Bluetooth is inoperable.

InTouch system boots normally.
Touchscreen "buttons" are greyed out for these functions. All other functions available in touchscreen work fine.
Audio/speakers do work - any sort of vehicle "tone" or "alarm" (such as the tone when opening the vehicle door or turning the accessory/key on) can be heard as expected.
Completed MOST Loopback test at the IAM module - clean test resulted in no change in symptoms, which led me to the TCU.

I've ordered a replacement battery so I supposed my answers will be learned as soon as I have time to swap out the old, but I saw this post and thought I'd ask anyway.

 

I never had any symptoms like yours, or any symptoms at all. The part was not expensive and these directions were excellent. After 10 years, I wasn't interested in taking chances with an original battery and having the car throw a hissy fit and want to be taken to the dealer for sorting.
Wishing you good luck and success with the replacement!

 

I never had those symptoms either. @cbodary If you add some vehicle information to your signature, it will help in any discussions like this.

 

Thank you for the suggestion. I've updated my signature.

 

It's not showing up yet, but maybe it's like PMs and you need five posts. I did peek at your profile and see you've got a 2016, so yours is likely in need of replacement. Maybe yours is past the "mostly dead" stage and is completely dead. As you say, you'll find out when you get your new battery.

 

I proactively changed out my nearly 10 year old Telematics battery following the instructions above... all was good! I tested my InControl Remote app with the car and all the remote actions worked... lights, door locks, etc. One last time before Christmas I drove the car about 10 miles, then came home and washed him and got him covered up for winter. Plugged in his Ctek. By that time the new battery had been in for close to 4 months of regular driving. (He has been in the garage since mid-Dec., now close to 2.5 months.)
I occasionally check the car via the Remote app and was then, a week or so later, surprised to see that last location where I stopped the car, was still listed as where the car was. It never registered that we had left that location and had driven home. Then the car was listed as 'asleep', but also ''in use" and so I couldn't have it do any of the horn or door lock functions. I did NOT do the SOS button 'reset' when I changed the battery as the car and Remote were all ok and the remote functions operated. I thought everyone was playing nicely.
However, that location is STILL shown in the app, the car is 'asleep' and I can't do any of the remote functions because the car is "in use". This was today after I took the car out for the 8 mile or so drive to work. The NAV functions are all good, the radio, all that. I went to Playstore and made sure I have the current version of the Remote app.
So tonight I did the SOS button reset. I'll check tomorrow to see if his correct location (my garage) is now showing. What else? I thought that telematics battery was like a backup battery, so pulling that TCU fuse 20 in the trunk would be of no avail.

Thursday AM update. Checked Jaguar Remote app and the car still thinks it's at its last stop before being driven home and parked.

 

Try logging out of the app then back in to force a refresh.

 

Yes, tried that. What I didn't do was perform the sos reset outside the garage. Maybe the old boy needs a clear shot at the Sat network?