This setting is on 726-xx-xx on every other car.
726-01-01 is the only of the usual blocks where this setting is present on other cars, but has the same value between cars that do this and cars that don't. On those cars (Focus ST for example) the 8th bit is toggled from on to off. That bit is already off in the AsBuilt data in every FiST I've seen.
Diffing the AsBuilt data between a 2014 that doesn't double-honk, and those that do not, I see differences in 726-04-01, 726-04-02, 726-06-01, 726-06-03 and 726-06-04. These seem to be the GEM (General Electronic Module) on most models I've found anything on. Unfortunately, every vehicle for which I've seen these blocks decoded has them dealing with BMS (battery monitor) settings.
I also see differences in 726-08-03. I've not found this to have been decoded on other vehicles. Its earlier cousin, 726-08-01 generally seems to deal with TPMS.
I also see differences in 727-03-01 and 727-04-01. These seem to be the ACM (audio control) on most models I've found anything on.
I also see differences in 737-01-02, 737-01-03, and 737-01-04. These seem to be the RCM (restraint control) on most models I've found anything on.
I also see differences in 760-01-01 and 760-01-02. These seem to be the ABSM (anti-loc braking) on most vehicles I've found anything on.
So, based on that, the one difference in 726-08-03 seems like a reasonable maybe. It's also possible that any of the bits that are on in 726-01-01 could be it and, perhaps, maybe it just didn't do anything in the early 2014 models. That wouldn't be consistent with how the FoST 194->114 change works, though, since the earlier cars without the double honk had 114. It's also potentially dangerous to start flipping those since one of them is likely to be the bit that enables push button start and could render the car impossible to start.
That's what I've got for the theory portion for today. I guess the next step is hooking up a cable and toggling some settings. I haven't yet worked up the nerve.
