SOS flashing and no connection to the app (TCU Problem)?

Ford Guides
1

Hello everyone.

Since I’m starting to get desperate, I’m trying to get some help here.

It all started when my 2020 ST occasionally wouldn’t start via the app. At the time, I assumed it was parked in a bad spot and had no network connection. When connected to Wi-Fi, i.e., when it was parked in front of the house, there were never any problems with remote start.

Later, the app started showing me a location that was weeks old. Remote start stopped working altogether after that.

Now, there’s no connection at all between the app and the car. The SOS light comes on every 40 seconds and then goes off again after 3 seconds…

However, I’m not getting any indication that there’s an eCall fault. There’s also nothing related to the TCU in the fault memory.

The modem is recognized and displayed in the Sync settings.

However, I get an error message when I try to activate or deactivate the switches in the Sync Analysis and Sync Diagnostics sections of the settings. This suggests to me that your modem is faulty, although it’s recognized and displayed in Sync.

I’ve read a lot about this and am even more confused. Everything related to the car’s internet connection seems to run through the TCU (Transmission Control Unit).

However, it also seems to have a battery that eventually runs out. That would best explain this “slow death” for me.

I would be grateful for any suggestions.

Even if someone is familiar with this, knows where the TCU is located, how to remove it so I can perhaps replace the battery. I’d rather not replace the entire TCU. It’s not cheap. And having it done at the Ford dealership would be unaffordable for me.

… One more question: This is the TCU I have installed:

TCU - Control Unit - Telematics Module
Part Number: LB5T-14G087-XH
Calibration Level: LB5T-14G087-XL (latest known: LB5T-14G087-XR)
Strategy: LB5T-14G139-SL

If I need to buy a new one, what should I be looking for? The part number? I can’t find anything ending in XH…

Thanks in advance for your help.

AND SORRY FOR MY ENGLISH, TRANSLATED FROM GERMAN

2

There’s no battery in the TCU its powered by the vehicle 12v battery.

Is this vehicle a NA/US import or an EU original?

The part number showing you more than likely won’t find directly, you can try to use ForScan 2.4.x )paid license) with a GOOD OBD2 adapter like an OBDLink Ex to flash the firmware up to -XR.

Pull the update files down first, the TCU files are one of the larger download, applying takes 45-70 minutes and the car needs to be on a battery charger the ENTIRE time with the engine not running (so that the idle shutdown doesn’t kick in and brick the module).

Even if you replace the module yourself, you’ll need to follow F150Chief’s doc regarding how to active a new TCU. The last 2 characters of the part number are usually current factory flash level and or a reference to the bracket is attached for mounting to the 4 screw holes as the same module can be in different models.

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3

Thanks in advance.

So it’s definitely an EU vehicle.

I have the full version of Forscan, so that wouldn’t be a problem, and an OBDLink EX. But where am I supposed to get the TCU update files?

4

In ForScan while connected to the internet, tell it to download unchanged files so that you have a copy of the current ones, these come from Ford’s site, NOT the TCU.

On the right top menu, select LB5T-14G087-XR, repeat the download to get that set.

Once you have those when you go to select to flash its not unusual for you to have to click the block and tell ForScan where they downloaded to on the laptop. Sometimes it in the Windows user download directory, sometimes in ForScan’s directory.

After you flash, the TCU will reboot, you also want to reboot the APIM after it comes back up. If you have a TCU reset option under Sync general on the vehicle center screen, hit it, it will clear your auth in Fordpass so that it can be recreated, if you don’t have the button do a master reset on the APIM.

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5

“In ForScan while connected to the internet, tell it to download unchanged files so that you have a copy of the current ones, these come from Ford’s site, NOT the TCU.” ??

Up to which version does that work? I’m using version 2.3.68 and as far as I know, it’s no longer available there. Can´t find it.

And there is no menu on the right and no chance to select LB5T…

6

Release version of forscan is 2.3.68, the beta version is 2.4.20

7

Lower versions offer more options… including battery choices. Version 2.3.34 has dozens of batteries to choose from. The higher version only offers four. So I think I need a older Version

8

TCU flashing has nothing to do with an onboard battery, Ford got rid of those a while back.

To flash firmware with ForScan you have to have a paid license and v2.4.x

9

I have a full version. The battery issue referred to older versions where you could select dozens of different batteries in the BMS, which isn’t possible with the current version. There are only two batteries to choose from now.

10

The BMS is not where you fix the type of TCU issue you’re describing.

That BCM setting really doesnt need to be changed from factory for anything unless you have done a large battery size upgrade and even then even most of the current valid factory Ford sizes will show unsupported/invalid in ForScan on models after 2019.

The only real setting of importance in the BCM is the battery age counter being reset after a new battery installation. If the age isn’t reset it can cause auto start/stop issues because the system still thinks it has an old battery.

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11

Thank you for your explanation. I just wanted to show that the older versions of Forscan had different options than the newer ones. The point was: “Pull the update files down first, the TCU files are one of the larger downloads.” This option isn’t available in my version. I’ve seen pictures of it here in the forum, but for some reason, it’s not possible for me. Or maybe I’m just too dense. That’s possible too.

12

My question is, should I look for an older version of Forscan to even have the option of updating the TCU? And if I find one, will my license still be valid? Or should I rather go to the Ford dealer and ask what they charge for a TCU update?

13

Updating firmware for any module requires a PAID Forscan license and you must be running a 2.4.x build of ForScan.

The paid license works with both 2.3.x and 2.4.x but only 2.4.x has the capability to flash a module.

Flashing is a function of the BUILD AND THE LICENSE.

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14

Thank you so much for your support and patience. I’ll download the beta and try it out when it gets warmer.