I have tried searching this forum but can't find a relevant discussion post so here it goes.
I have a 2016 Fatboy S (ABS, Electronic Cruise Control). I bought it brand new in 2016.
For the first two years (~25,000 miles), everything was great. Then, in 2018, the rear brake engaged while in the mountains of Colorado near Aspen. I was riding two up and did not notice the drag -- just thought it was a steep climb and we were fully loaded -- until I got to the top of the mountain and rolled into Aspen. By then, the heat boiled out all of the brake fluid and melted the rubber lines. The pads were shot. There was no brake at all. It was a Friday and everything in Aspen was closed.
So, we canceled our weekend and headed to Denver (Avalanche Harley). Spent six days there as they order parts. New lines, new caliper, new pads, rebuilt master cylinder, etc.
Made it back home (North Dakota).
In 2019, the same thing happened again.
Then again in 2020 (third complete overhaul of the brake system - this time replaced the ABS modulator).
This past weekend in 2021 it happened again.
I have been to four different dealers. Harley does not have any tech reports on that model (there was a complete recall on the Road King which used the same ABS and cruise control system as the 2016 Fatboy S). I have been on the phone with Harley in Milwaukee. Nothing. No one knows anything. Harley Corp says they can do nothing for me.
Does anyone know of a similar problem with a 2016 Fatboy S with ABS?

 

I have a 2014 Fatboy w abs. I had only had it a year (had 30k miles on it when I bought it) when the front brake locked up. The front master cylinder was replaced bc the inner bore was scored. Still was locking up. They replaced the abs module. It hasn’t locked up since, but I don’t get a lot of miles on it either. It was not cheap. Good luck on your bike.

 

Thanks. The ABS module is brand new (last year) and it is still doing the same damn thing.
I am seriously disappointed in Harley. The service managers of the four dealers I have been to are great but they are flying blind, too. The engineers in Milwaukee ought to be looking into this. Anyway, this winter I have a decision to make: stick with Harley or switch to an Indian.

 

I'd want to have pre-ABS brake equipment fitted. I'm not sure what that would involve, particularly how to fool the onboard computer.

 

So I have a Fatboy S 2016 also, not quite the mileage you have though. Never had this issue, but my rear bearings have gone out on me twice and needed replaced. And this was while the bike was under 10000 total miles. On my third set now, and hoping not to have these replaced anytime soon.