OK, I can try that. There’s also “vehicle reset” on the GAP tool, is that worth trying you think? I’ve had to drive the car every day to go to work so I haven’t been able to let it go to sleep mode. In fact I’m not sure it’s ever been in sleep mode, I’ve never noticed that in the JLR app. I do have a noco trickle charger, I’ve been using that.

I also did wire a noco eyelet harness to the jump points under the hood and zip tie it out of the way, I wondered if maybe that somehow affected the ACC system but I can’t imagine how, and the fault codes seem purely software oriented, they don’t describe a blocked or blind sensor or something, it’s all communications/messaging between units in the car.

I did un-do the CCF for the WiFi because that seemed to be what messed up the ACC, and in my queries with AI (which may or may not be accurate) it seemed to think that the WiFi change would involve telematics that could disrupt the ACC. So now the only changes I’ve left are the key fob tailgate release, the splash screen, and the auto start/stop memory. I can’t imagine any of those have anything to do with ACC.

 

I'm no expert so I can't tell what the vehicle reset on the GAP tool really does. Maybe send an email to them asking. You don't want to brick your ECU modules. Having the battery well charged is a must, these cars have so many sensors everywhere, a drop in voltage can throw codes and many times they cascade. The eyelet should not be an issue as long as they don't short. I also have one I've made for my ctek and I used a thermal protector tubing around those wires, can't have them melt and short while driving as engine bays get really hot. The zipties I used are also high temp rated. As for the wi-fi I really don't know, it starts getting into software code that frankly I don't think anyone is really familiar with.

 

I sent GAP an email. After the error appeared the only thing I’ve done so far is to revert the WiFi hotspot change and that hasn’t fixed it. I was thinking I’d revert all CCF to original using save/restore but at this point maybe the best thing to do is to wait until GAP replies and see if they have an idea, and in the meantime I can let the car go to sleep mode. I also see that disconnecting the battery for 15 min or so will allow the modules to reset, so maybe I could try that. At this point I’m just very nervous about bricking anything. Was all excited to customize after dipping a toe in the water with the splash screen which seemed to work fine, but this experience has tossed a wet blanket on my enthusiasm. Now I just want to get the car back to factory settings and have everything working.

 

Patrick from GAP came to the rescue. Apparently changing the splash screen (EUCD-205 Racing Sub Brand) was the culprit. This cannot be changed on model year 2026 and there is no workaround.

He didn’t elaborate as to the cause but I’m guessing this branding is not purely cosmetic and is something that is checked between communicating ECUs in the new model year, and so must remain internally consistent. The faults I saw appear to suggest that an inconsistency broke communication between the DADC and other ECUs leading to the adaptive cruise control failure. That’s my amateur interpretation, anyway.

Patrick says to their knowledge all other changes should work on a 2026 in markets where JLR have not locked the CCF down via Secure Diagnostics.

Hoping this information helps anyone else who accidentally breaks their car trying to get the silly 007 logo to pop up.

 

That's interesting, good to know and thank you for sharing. Hopefully you'll get everything normalized, share here if it all possible. As long as your battery is charged, the chances of bricking the ECUs is minimal. I'd guess only if you pull the tool from the OBD port interrupting an upload, that could cause some serious issues.

And it is very possible JLR might have changed a few things internally to accommodate the locking of the CCF files in some countries, hence the no-go on changing the splash logo on '26 models onward.

 

Yeah reverting that one CCF change to “mainstream vehicle” fixed all my problems. Crazy, it’s the last thing I would have suspected. It’s ironic, this is the very first thing I changed, thinking it would be the lowest possible risk.