Mondeo Mk5 - TPMS/External Temperature/Climate/Windows gone

[Magebarf]

Hi!

I’ve tried searching all over internet, including this forum, for anyone describing the same problem as I was observing but could not come up with anything. That’s why I’m posting this in case someone else runs into the phenomenon.

So, to set the stage: Car is a Mondeo Vignale, MY2017, Automatic, Diesel. Generally been working without any issues for the last year and a half I’ve owned it.

Yesterday, a little over half way during a semi-long tip of total 200km, we were pulled over for a routine police control, shut the engine down, put it into parking afterwards, and without opening the door (shutting things off) starting the engine back up and rolling out.

Nothing too strange there, but just a minute after we rolled out we get a error for the TPMS not working (not a warning for a tire having bad pressure, but the entire system having a fault), and I notice the external temperature now reads as “--°C”.

A little further down the road notice the windows fogging up and when trying to fix this I notice the entire climate system control button section is not lighting up. Intermediate step is to try opening the windows, but the electrical window motor (or the controls) do not respond.

So, after stopping, turning off engine, opening the door and letting the car power down all systems to see if things are reset, we realize this does not solve anything. The errors stays, and keep showing up every attempt we do.

With a few stops to manually ventilate to get rid of  the window fogging (pull into a parking spot and open the doors), we reach the destination. When locking the doors I notice the side view mirrors do not fold.

I leave the car locked and untouched for first 1 hour and then over night with hopes that it will go to a low enough power mode that all ECUs will have been reset, but this does not have any much effect.

This morning the TPMS error no longer shows up, but all other issues seems to remain. Additionally I notice some flicking in the lights around the climate control panel, for short periods of time the increase the brightness and then go back.

So, now at our destination I do have access to some tools, so first order of business is to measure the battery voltage that comes out at 12,39V, a little on the low side. My theory: The error itself may have stoped the ECUs from going into low power mode, thus draining the battery a bit over night.

Next we detach the 12V battery, leave it disconnected for 1-2 minutes and then reattach it; Problems are all gone!

I sadly do not have any OBD interface available here, so unable to read out any DTCs, but at least the power toggle seems to have reset the error. Temporarily or not is the question that will have to be seen.

My theory, which is why I went with a battery disconnect: One of the ECUs connected to a specific CAN bus went haywire, and disrupted the entire communication on that bus. This leads to trouble for all nodes communicating what is supposed over that bus, and additionally can hinder the ECUs from going to sleep. The battery disconnect was intended to cause the problematic node (whichever it was) to be reset.

So, in case anyone else encounters a similar problem and tries to find info about it; at least there’s a random guy on the Ford Owner’s club forum linking issues with all these systems together and “solving” it with a short 12V disconnect.