I just learned that on my 2016 DS the heated floors are protected by a GFI plug. The service technician told me that this was new for him. He only found this out after asking engineering for drawings. This information may not be helpful for you specifically, but I just wanted to put it out there in case it may help others.
On second thought, sometimes these changes do not have a hard start and stop date. It could be that during late production in 2015 they had implemented this change. So I guess it is something you could check also. I know somebody is going to ask me where those GFI plugs are located, to be honest, I never asked the technician.
2020 Newmar Dutch Star 4310 on Spartan Chassis
2017 Lincoln MKX
Owned: '15, '16, '17, '18, '19 Dutch Star