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Model S intermittently loses 4G/LTE/network connectivity while powered off

tefla

Member
Jul 22, 2021
18
3
Norway
I think it’s the other way around: It needs to be fixed in software but they don’t see this as a priority.
Could be.

But I highly doubt everyone with a Tesla experience this problem, so isn't the logical conclusion that deep down it's a hardware issue? The software is the same, right?

Apparently the modem is being reset on multiple occasions by Tesla, probably to circumvent another bug (ie a memory leak) so fixing the underlying bug would allow Tesla to stop reserting the modem and would give us a better connection.
Do we know that?

As to why Tesla still doesn’t force a rejoin of another network when crossing a border… I live very close to the border and sometimes it takes up to 15 minutes to join the “right” network.
This happens to me too. Annoying, but thankfully it is a rare event for me.
 

Rayminster

Member
Feb 11, 2019
93
16
England
My car goes through spells of it happening every single time I leave the car to every few days leaving the car.
At the moment unfortunately, it’s from the moment I close the door until the moment I open the door.
I once lost my keys and in order to get the car to wake up, I literally push the handles a few times and the car became aware there was activity (as I heard the contactors snap) then 5min later, the car connection came live and the app responded and therefore unlocking yo let me in.
A very long winded way to get in the car.
 

Zuikkis

Member
Aug 19, 2020
268
321
Finland
What model year cars do you have? I have the same problem on a 2013 car with MCU2 upgrade.

I spotted this on some other thread:

What they don't tell you about the MCU2 retrofit is the higher vampire drain on pre-Q2-2015 vehicles because the battery packs don't have the standby power supply DCDC which powers the MCU's standby power and body control module directly from the HV battery. The standby supply means the main contactors can stay open (saving ~20-30W IIRC). Without it they have to stay closed, a pump has to run to cool the DCDC, etc. (Yeah, a pump has to run any time to contactors are closed to circulate coolant through the DCDC... so... yeah).

MCU2 was only originally installed in cars with this standby supply and seems to behave... oddly... in cars that don't have it. As in, it stays awake more than it should.

I figure they'll fix that eventually.

If the problem is only in pre-Q2-2015 cars then it could be related to this? There must be some kind of trade-off between high vampire drain and deep sleeping the MCU (loosing connection)..
 

neopav

Member
Apr 16, 2009
15
5
Hi,
don't worry, as far as I can tell this is only a software problem, and there is a simple workaround to turn the car on IMMEDIATELY with the app.
I know that this is only a software problem (waiting for a fix from Tesla... ;) because I actually own a 2017 Model X P100D, originally with an MCU1.
I upgraded that with an MCU2 (plus AP3 hardware, having bought the FSD package back then) on october 2020 (my car was the first Tesla being upgraded MCU1 -> MCU2 here in Italy).

With the original MCU1, as anybody knows, there was a switch with selectable "always on" cellular connection.
With the MCU2 (and its new software) this switch disappeared. But I can confirm that the car, upon waking with the app, was EVERY TIME immediately reachable with the phone.
Also, when I started the car (and I make several stop and go every day, say 20-30 times per day), the LTE line was immediately working, every time.
Then, with the first software update of 2021 (it was a january/february update), a strange behaviour appeared.
I have now the latest update available for my car (2021.12.25.7), and this is the same: when the car is woken up (either by using the app, or when you open it and seat to start driving), it will start all its systems immediately. But for connectivity, only wifi will be readily available, and instead the LTE connection will start after max 3 minutes later.
I confirm that back with the old 2020 software for MCU2 the LTE connectivity was readily available, ever: so you can be sure that this is only a software glitch, that I hope will be addressed soon!

Now, this WORKAROUND for connecting immediately with the car.
When you open the iOS/Android app, a wake-up sms will be sent by Tesla to the car.
The car will wake up immediately, but it will not be LTE reachable for at least 3 minutes.
But if you are near the car with your phone, and you have your hotspot activated on the phone itself, the car will connect immediately to it (obviously, you have to had connected before the car with that wifi hotspot).
Tested several times: the car will be reachable within 15-30 seconds upon starting the phone app!

Hope this trick can help you, in the waiting for Tesla to bring an updated software to the car that can address this...
 

wk057

Vendor & Senior Tinkerer
Feb 23, 2014
5,740
12,314
Hickory, NC, USA
I know that this is only a software problem (waiting for a fix from Tesla... ;)

Unfortunately, on pre-Q2-2015-ish vehicles, it's not a software problem. It's a lack of hardware required for low-cost sleep. They've been trying to optimize this a bit with a bit of crude predictive stuff trying to determine when to be at the ready and when not to be, but there's just not a lot they can do on earlier models that lack the in-battery standby power supply.
 

AustinP

Active Member
Apr 6, 2015
1,339
1,078
Belgium
Unfortunately, on pre-Q2-2015-ish vehicles, it's not a software problem. It's a lack of hardware required for low-cost sleep. They've been trying to optimize this a bit with a bit of crude predictive stuff trying to determine when to be at the ready and when not to be, but there's just not a lot they can do on earlier models that lack the in-battery standby power supply.
MCU1 had no issue with that old battery.
Why would MCU2 have an issue? I may be simplifying things as I have not much clue, but would restoring the software functions “Power management” like below providing connectivity “always on” and energy saving mode controls not be the solution?

371F854F-9E0B-4CEF-AE8B-F7D16202DED7.jpeg
 

wk057

Vendor & Senior Tinkerer
Feb 23, 2014
5,740
12,314
Hickory, NC, USA
MCU2 was designed with the standby supply in mind and thus doesn't have the same hardware abilities for power saving. For example, the modem, gateway, and CPU are able to be powered directly from the standby supply in the pack. In an older S, this has to happen from the normal 12V system without hardware for any intermediate modes. Based on my understanding of the hardware, a retrofit capability wasn't planned so no need for hardware capable of significant power saving was required. The savings of not requiring closed contactors and DCDC enabled outweighed any potential benefit by an order of magnitude.

Then when these units are in older no-standby supply cars they're wasteful since they use more power AND the contactors need to be on and cycle.

MCU1 was designed without the standby supply in mind, so was designed to not require continuous power for a lot of functions along with hardware controls to keep portions in lower power modes.
 

Rayminster

Member
Feb 11, 2019
93
16
England
MCU2 was designed with the standby supply in mind and thus doesn't have the same hardware abilities for power saving. For example, the modem, gateway, and CPU are able to be powered directly from the standby supply in the pack. In an older S, this has to happen from the normal 12V system without hardware for any intermediate modes. Based on my understanding of the hardware, a retrofit capability wasn't planned so no need for hardware capable of significant power saving was required. The savings of not requiring closed contactors and DCDC enabled outweighed any potential benefit by an order of magnitude.

Then when these units are in older no-standby supply cars they're wasteful since they use more power AND the contactors need to be on and cycle.

MCU1 was designed without the standby supply in mind, so was designed to not require continuous power for a lot of functions along with hardware controls to keep portions in lower power modes.
That’s really disappointing, I might ask Tesla to give me back my mcu1.
You’re right about the contactors , I hear them snap to start each time I get in the car
 

Zuikkis

Member
Aug 19, 2020
268
321
Finland
I confirm that back with the old 2020 software for MCU2 the LTE connectivity was readily available, ever: so you can be sure that this is only a software glitch, that I hope will be addressed soon!

I think you are correct. I also got my MCU2 almost a year ago. I don't remember any connectivity difficulties back then, it must have started in 2021.

So maybe there is a fix coming.

But I think this really is caused by the lack of standby supply in older batteries. Tesla is balancing between complaints about increased vampire drain and bad connectivity.

I guess they could reintroduce the "always connected" checkmark in the settings, so each user could decide if they accept the increased drain to get better app connectivity.
 
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Gumball

Member
Mar 9, 2020
292
345
Yes
Same problem here, but not every morning, or every time I get in the car. LTE takes about 2 minutes to connect sometimes. Not a huge problem for me, the MCU 2 still is much better and faster then the MCU 1 was in my 2013 car,so the 2 minutes don’t bother me to much. Maybe there will be a software solution one day, lets hope so.
Weirdest part is that the problem only started about 3 weeks after the MCU upgrade.
 

Rayminster

Member
Feb 11, 2019
93
16
England
I have news. I went to Tesla sc today for other issues and again reported that lte problem. They said they have a new bulletin for a firmware upgrade that addresses Tesla app connectivity problems.
They said they’ll run the update as well as fix my other problems.
I’ve screen captured the firmware version now and I’ll confirm the new version and report back after if it works!
 

AustinP

Active Member
Apr 6, 2015
1,339
1,078
Belgium
I have news. I went to Tesla sc today for other issues and again reported that lte problem. They said they have a new bulletin for a firmware upgrade that addresses Tesla app connectivity problems.
They said they’ll run the update as well as fix my other problems.
I’ve screen captured the firmware version now and I’ll confirm the new version and report back after if it works!
I have a ranger coming next week, if you could confirm and share the details of the version, I’ll ask him too.
 

neopav

Member
Apr 16, 2009
15
5
Hello,

right yesterday night I received a new update for my 2017 Model X with MCU1 -> MCU 2 upgrade.
This new version is n. 2021.24.4.

I installed it this morning.
Now, I just approached the car with only the key with me (no wifi reception for the car).
I opened the door, and I saw that the car was really in a deep sleep state (it took almost 10 seconds for both screens just to light up, they were totally black!).
But to my surprise, LTE connection was immediately available!

I need to test this just a little bit more, but I think that our problem is now addressed...
Is Tesla reading this forums? :)

Finger crossed!
 

neopav

Member
Apr 16, 2009
15
5
I have news. I went to Tesla sc today for other issues and again reported that lte problem. They said they have a new bulletin for a firmware upgrade that addresses Tesla app connectivity problems.
They said they’ll run the update as well as fix my other problems.
I’ve screen captured the firmware version now and I’ll confirm the new version and report back after if it works!
Rayminster,

do you confirm that the firmware version the SC detailed to you is the same that I installed today? (v2021.24.4)
 

Rayminster

Member
Feb 11, 2019
93
16
England
Rayminster,

do you confirm that the firmware version the SC detailed to you is the same that I installed today? (v2021.24.4)
The version prior to my sc appointment is 2021.12.25.7 and it consistently goes to sleep when I close the door and walk away. Meaning I get no instant app access and is very hard to to wake the car up.
When returning to the car with the key, the lte will be in disabled state until a few mins pass by of being inside the car.
Tesla still have my car today and will be done by tomorrow as they have lots of cars to get through.
Fingers crossed tomorrow, they have deployed a newer firmware version and hopefully it actually works.
As far as I’m concerned, mcu was able to keep lte in standby mode so no reason why they can’t get mcu2 to work also. (Enough to keep the lte board awake for app access).
 

Rayminster

Member
Feb 11, 2019
93
16
England
Tesla service centre are USELESS. Putting the lte connectivity aside. The whole operation of the service centre is flawed.

the customer speaks to reception > reception text the engineer > the engineer replies on the computer to reception > the reception text back to the customer and the whole communication goes around in circles.

I’ve asked a very simple request;
“can I have a quote for the headlight bulbs to be replaced as one of them is burning out”. The engineer text back the reception saying, “they don’t supply bulbs so I need both entire headlight units replaced at a total cost of £2144. The new bulbs come inside the new headlight units”.

my analogy to the reception,” if my cooker bulb blew, would it be reasonable that I buy an entire new cooker? “

anyway, that rant aside, they have upgraded the firmware and they say (through their stupid text channel) that it’s resolved.
 

Rayminster

Member
Feb 11, 2019
93
16
England
Ok folks, here’s what I have to report. Tesla did the firmware update but the version number hasn’t changed so it’s appears like nothing really changed just by looking at the version numbers alone. HOWEVER!!!! When I get out of the car and walk away for a bit for the car to do it’s usual sleep and lte disable behaviour, I then tested the app.
From a far distance, I opened the app on my phone, and it’s loading and taking its time, then all of a sudden I can here from a distance the cars contactors snap and then the app comes online.
So what ever change they made, it seems to wake the car out of sleep and then trigger the lte modem to come online. I think it must be something to do with SMS triggers.
Anyway, it works but it is a workaround and not a fix.
I’ve attached the the job sheet from Tesla
 

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Zuikkis

Member
Aug 19, 2020
268
321
Finland
From a far distance, I opened the app on my phone, and it’s loading and taking its time, then all of a sudden I can here from a distance the cars contactors snap and then the app comes online.
So what ever change they made, it seems to wake the car out of sleep and then trigger the lte modem to come online. I think it must be something to do with SMS triggers.
Anyway, it works but it is a workaround and not a fix.

Hmm why do you think that is not a real fix? I'm pretty sure that's the only way it can work, and the exact way it worked with MCU1 too. App connectivity requires MCU to be alive, so if it is sleeping it must be waken up.

Good to hear it works now. My car is just installing an update at the moment, I hope it fixes it for me too.
 

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