[C5 X7] Replacing / upgrading the emergency calling BTA module & teardown of the old one

[the-termin8r]

About a week ago I had this video crop up on my YT. It's a guy swapping out his emergency calling BTA module for a more recent BTA2 (part number 9815911880-01). For those that don't know, a lot of the older PSA cars that had emergency calling had the network decommissioned a couple of years ago. In the case of the X7, the SOS button would flash orange for a minute or so when you turn the ignition on. As it turns out, there are multiple revisions of ECU, some of which haven't been decommissioned yet and still work for the time being.

As these seem to go for about £30 second-hand I decided to give it a try. And on the surface it looks to have worked. The SOS button no longer flashes orange. Diagbox sees the ECU but says "ECU not recognised." In spite of this I can go into its settings to flash the VIN and I can see the various parameters. As far as I can tell it works and I'm going to chalk it up to Diagbox 7.62 being a bit too old to properly detect the ECU. The installation was dead simple. Pull off the fascia, pull out the old BTA module, stick in the BTA2 in, run a scan, flash your VIN to it, re-run the scan, put the fascia back on, job done. With that being said, if I were in a crash, there's no way in hell I'm actually going to rely on this to call the emergency services.

Out of interest, I decided to tear down the old module. The new one I picked up is a Magneti Marelli made in France, the original is an Autoliv made in Sweden. Both reputable brands, so no complaints there. I didn't tear down the new one, but I can say that both have a built-in speaker and an 18650 cell. The speaker is presumably for when the HU is disconnected in a crash (the car triggers an electrical cut-off from what I know). Same story with the cell. Diagbox says that with the current state of the cell in the new one I should have over 15 mins of communication time. Presumably the module powers the mic in the ceiling.

The casing is only held together by simple (and visible) clips, but was a pain to get into because most of them have to be released simultaneously. Once inside, there isn't actually very much to see. Part of me was expecting to find a SIM, but there wasn't one. There were a couple of EMC cans and large portions of the board were covered in epoxy conformal coating. That's about it. I don't actually know what to do with this thing now. On one hand, I don't want to bin a perfectly good PCB, on the other, it's a useless brick since the system got decommissioned.

[mickthemaverick]

Interesting Rob, I'd forgotten all about that system!!

[wurlycorner]

TBH I've never known much about what this system was meant to be/how it would work! (And I assumed it was only supported while you had a Citroen warranty/extended warranty valid?)

[the-termin8r]

It became a legal requirement to have eSOS in the UK from 2018. Though the older Citroen system patches you through to their call centre where they give the details to the emergency services. I read that in countries that don't fully support the system (i.e. outside the EU) you get patched through to the ES directly, but without them getting any of the telemetry data. The Citroen support thing might potentially be tied to the warranty, but I doubt they would have done it for the emergency calling. The handbook doesn't mention any such limitations either.

[EDUCAR]

I've made this upgrade to the BTA 2.0. What is missing in the video is that you may/should also change parameters in the "configuration of the vehicle options" BTA menu.

In my case I got the BTA from a French 2016 Citroen DS4, so I changed:

"Choice of nationality of driver";
"Vehicle track width (in mm)";
"Adjustment of the loudspeakers as a function of the passanger compartment";
"Level of speed compensation" and
"Rear wheel radius (in mm)"
(I used the paramenters from my 2011 C5 "old" BTA)

The other parameters where the same in both the "old" and "new" BTA, so they remain unchanged.

[the-termin8r]

I only had the track width parameter in mine but I left it as is. I might go back in at some point if I can be bothered to open the dash again.