TCU firmware downgrade

Thanks your reply, that gives me hope that this K series TCU should work with firmware downgrade to J series, do you know where can I get the JL3T or JX4T firmware?

See your messages…

You might want to check this article FordPass and Fusion Energi, 4G EUR TCU
It contains all the needed files to downgrade K-series modems to J-series. I did it myself and everything went smoothly.

Thanks F150Chief and JoSS.

Just an update, after downgrade firmware to JL3T, APIM is able to see TCU, the ESN shows up, and the TCU status can change from “Factory Mode” to “Wait for Authorize”, one day later “Activate Vehicle” button shows up on my Fordpass, however, when I click it, it always says “Activation is currently unavailable”, any idea why it doesn’t let me go through?

Sometimes this is due to the app just getting stuck at a point in the activation process, or several attempts were made to activate the vehicle, causing a jam in the process.

DO NOT try to activate the vehicle more than once.

Do this:
Remove the vehicle from FordPass.
Delete the app on the phone and reboot the phone to clear the app cache.
Perform a Master Reset on the APIM. This will reset the activation process and deauthorize the vehicle.
Re-pair your phone to Sync.
Install the FordPass app on the phone.
Important: Start the vehicle, engine running.
Add the vehicle to the app. You may need to restart the app to see the vehicle once added.
It should ask to activate the vehicle.
Accept the prompt on the Sync screen. The phone app will say activation pending.
Important: Leave it alone, don’t go pressing buttons, etc. Just wait, it takes a while to show the vehicle as activated sometimes.
If the vehicle does not show as activated after 10-15 minutes, log out of the app on the phone, close the app completely. Open the app and sign in. Usually this will kick start a refresh and the vehicle will show as activated.

If the above does not work, then go thru the activation process in this doc starting with changing the TCU back to factory.
APIM & TCU Files and Programming 20220108.pdf (511.8 KB)

Got it, his instruction really helps! looks like the firmware for TCU is good, but I don’t quite understand the firmware of APIM, the instruction says the APIM firmware version should be the 3.2/3.3 APIM Navigation Unit Firmware, is it Sync 3 software version? mine is 3.0 currently.

Screenshot below is the firmware of my APIM, the instruction says the minimal Strategy and Calibration is 1U5T, but mine is GB5T, is it good or not?

If you are not interested in the Hotspot, this is really option. Although, that firmware is pretty old. Since you already mastered the TCU, which is a hard one actually, tackling the APIM is not that bad. You have very early firmware on the APIM, which will not show any info about the TCU, other than the TCU serial number. The firmware requirement for the TCU addition is really only for the Hotspot but will help with other things in general. You can stay at the current firmware, if you choose.

Look at this article: APIM Firmware Production Releases - Ford / Information - CyanLabs Official Community

You are currently at:
3.0 APIM NAV Unit Firmware (Production Release, 2016-Early 2017, G thru Early H Series)
Secondary Boot Loader: GB5T-14G376-AA
Strategy (F188): GB5T-14G374-CA or GB5T-14G374-CB
Calibration (F124): GB5T-14G375-DA or GB5T-14G375-FA
ECU Configuration/Sound Profiles (F10A): GB5T-14G379-AA
ECU Configuration/Illumination Strategy (F16B): GB5T-14G379-BA

You can safely go to
3.0 APIM NAV & NON-NAV Unit Firmware (Production Release, 2017-Pre-2018.5, H thru Early J Series)
(Originally Found On 2017/Early 2018 Units That Ship with 2 USB Ports on Back)
Secondary Boot Loader: GB5T-14G376-AA
Strategy (F188): HB5T-14G374-CA
Calibration (F124): HB5T-14G375-DA or HB5T-14G375-FA (NAV) / HB5T-14G375-CA (NON-NAV)
ECU Configuration/Sound Profiles (F10A): GB5T-14G379-AA
ECU Configuration/Illumination Strategy (F16B): HB5T-14G379-BA
3.2/3.3 APIM NAV & NON-NAV Unit Firmware (Production Release, 2018.5, Late J thru K Series)
Secondary Boot Loader: GB5T-14G376-AA
Strategy (F188): 1U5T-14G374-DA (6/27/2018)
Calibration (F124): 1U5T-14G375-DA (NAV) / 1U5T-14G375-CA (NON-NAV)
ECU Configuration/Sound Profiles (F10A): GB5T-14G379-AA
ECU Configuration/Illumination Strategy (F16B): JB5T-14G379-BA (6/7/2018)

Thanks your always prompt response! can you share the APIM firmware with me (the 3.2/3/3 if that works for my APIM hardware)? I’m going to upgrade APIM after activate Fordpass.

See your messages…

I saw your post on F150Forum:

Not sure if this has been mentioned but if you connected the antenna bought from Amazon or left the 2nd antenna port open, you may have some DTC error codes from TCU, they may indicate the primary and 2nd antenna open circuit, it won’t impact anything I guess because the antenna is connected actually. To get rid of these codes you will need add a 10K ohm pull down resistor on the antenna input wire. I figured it out by tearing down a shark fin antenna, it has a 10K resistor right after antenna connector, and if you use a multimeter to measure the voltage on TCU antenna input, you will find it has 1.8V DC on it, so by pulling this voltage down a little bit (~1.2V), the CPU in TCU will consider the antenna has been connected. I added a 10K resistor on both antenna ports, and the error codes in DTC are gone, it’s clean now.

So did you consider that adding the 10K ohm resistors to the antenna line feed would change the frequency response of the antenna? It does, but in this case the antennas you used have a very wide frequency response, so the affect would be marginal. (That’s why they are cheap antennas.) This probably shifted the response curve lower in frequency.

If you did this with a quality narrow band open receiver antenna it would not work. To negate the affect a bit, connect the resistors where the feed line attaches to the antenna itself.

However, all is well, so success.

Good point, I think it depends on the characteristic of the resistor you’re using when it is working at RF frequency (up to 3GHz), if you’re using a small (0402 or 0603) SMT 10K resistor, I’m pretty sure it will not impact antenna at all because the resistor will behave consistently as as a pure resistor, meaning no inductance or capacitance characteristic at RF frequency, and given the RF impedance of antenna and cable is 50 ohm typically, the impact of a 10K pure resistor should be negligible.

I used to work as a RF engineer, and did impedance matching work for mobile phone RF transceiver and PA, at that time the mobile phone antenna are external and we often add a shunt inductor to protect PA from ESD damage, so I don’t see any risk to adding a small 10K resistor on RF line.

As I said in the post, there is a 1.8V DC on TCU antenna port, and if you short it to ground, the current is only 0.3mA, so I believe it is for antenna attach detection purpose, i.e. there should be a pull down resistor in the Ford factory antenna (shark fin or PIFA), otherwise there is no way for TCU to detect antenna attached or not.

Agree. There is no harm in this case with these antennas, and if there is a frequency shift it certainly will not be much, especially using the SMT type resistors vs the carbon or mica series. So the shark fin must be an externally terminated antenna if they are using a resistor. This means of course that the receiver input is high impedance, or not terminated. At least that is what it appears to be…

This stuff has come a long way from sloping V and nested rhombic antennas I used in the service…

Finally after few days waiting, my car is activated, and I can remote access my car through Fordpass now, big Thanks You to people who helped me here!

One more question, my Sync is still 3.0 right now, I plan to upgrade to 3.4 with latest maps, do I need reactivate after upgrade?

Yes, but it should be nearly instant. It’s really the first time that takes forever sometimes.

Not sure if I can ask here, but after upgrade to Sync 3.4, the Sirius XM traffic information is no longer show up, it works normally before upgrade, did I missed something?

Perform a Master Reset. What version of Sync 3.4 did you install? Should be 3.4.22251.

Sometimes it will take a day or so for them to populate back.

Yes, I upgraded to 3.4.22251, and did a master reset. When I check SiriusSM in Apps, it only says Audio is Subscribed, all other services (including Traffic) are Not Available, I did have 3 months trail which will end next Jan, anyway, I’m going to wait few days and see if it will show up.

Back to the TCU topic. I checked the TCU data service on ATT website with donor VIN, looks like I can have 3 months trials, so I decided to give it a try. I upgraded APIM firmware to 3.2/3.3 per the instructions from F150chief (Thanks again!), and after upgrade, there are some AS build checksum errors, I loaded the default configuration the errors are gone. Now the WiFi hotspot shows up on Sync, and I’m able to change SSID and password.

My question is: is AS build part of firmware or not? probably not I guess, if that is the case, how do I know if my old AS build data can work normally with new firmware? is the new firmware backwards compatible with old AS build data? if not, do I need to manually change the AS build data to make sure it will work with new firmware?

There are 3 parts to the module programming:
Firmware is the base level instruction set for the module hardware, in the strictest sense.
Software is the module interface for HMI and other functional interfaces, like networking, etc.
Asbuilt Data is the option or feature set for both firmware and software, or either depending on the module.

Firmware and software changes over the life of the module or program. This is due to updates, features, etc. It is important to understand that this makes the asbuilt data change accordingly along with the changes to the firmware or software. In some cases, like the TCU’s, the asbuilt changes in accordance with the features changed or added in the TCU firmware. This is natural and to be expected. The good thing is that 99% of the time the old asbuilt data is still valid, even if there are additions to the feature set for the asbuilt. Usually the new data lines will just be ‘0’ or null, so no issues arise with the older data.

As a general rule, you should always reload the asbuilt data whenever any change to the firmware is made. This is due to firmware changes that may affect instruction addresses and such. Make it a practice to do so.

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