X5 Trailer Hitch module coding success

[AtomicRob]

I wanted to share some info about my experience coding for the trailer hitch module. I followed mostly the steps in the esys docs as well as a helpful video on Youtube: youtu.be/HET0KPY3FVE. Huge thanks to shawnsheridan for the helpful links and info, couldn't have done this otherwise!

Prior to coding, I got a Curt hitch installed at a local shop, then I bought and installed the OEM wiring harness and trailer module. Once that was done I had the expected trailer warning on the dash, so it was time to code. After much research I felt confident enough to do it. (Caveat... I've been a software engineer for >25 years and have flashed more firmware than I care to admit. Still, this was a pretty intimidating process.)

I bought an enet cable from Amazon. I set up a spare Windows 10 laptop with mostly default settings except: turned off firewall, turned off Windows Search indexing, disabled wifi adapter. Installed E-sys and the full psdzdata. In the video above and some docs I read elsewhere, it seems like it's necessary to flash the trailer module (AAG) after VO coding so the full psdzdata was needed. I set up my car on a battery charger just in case - it's a hybrid xdrive40e so I think the 12v batteries would have stayed charged via the dc-dc converter anyway but better safe than sorry.

Things went according to plan until the very end. I had already added K235 to HO-WORT, and VO coded the whole thing. Then prepared to flash the AAG module, and at the last step. where I went into Expert Mode/Tal Processing screen and after following the steps and selecting only the AAG module to update, I pressed Start... and after a couple minutes it failed with a error that I unfortunately forgot to copy down but it was something about "psdz tried to determine the network topology" I thought that sounded connection-related, and it was... and after trying several times to disconnect/reconnect in different ways (via Gateway URL, via VIN, etc) I finally noticed something weird in the connection target list. There were now two sets of targets for F025, where originally I'm pretty sure there was just one. Or I had only noticed the first one?



So I tried selecting the second one in the list instead of the first one, connected via VIN, and it worked! Took about 5 minutes (a very long 5 minutes!) I'm still not sure of the significance of the two targets but if anyone else runs into this it may be helpful to know to try the other one.

Afterwards, there were a whole lot of DTC codes getting generated, as expected. I used a free Andriod app called "Car Scanner" (which does have a cofiguration for BMW and can see all the modules) with my VEEPEAK OBDCheck BLE to reset the trouble codes, and now it's all cleaned up, no CEL or trailer warning. I haven't hooked up a trailer yet but I checked with a DMM and I'm getting the expected voltages on the plug, so looks like it's all good to go.