Whoo-Hoo mine finally worked today.
I was having the same concern as some others with my 2015 Overland that FCW was not working with ACC Off.
I have seen the FCW Warning a couple times to !! BRAKE !! when ACC was on.
But it has never warned me with ACC off.
Never isn't so long though 4 weeks and 1100 miles. I have tried to test it numerous times and nothing. It felt beyond comfort zone. What was bothering me is, if it was any later it seemed a bit pointless. And it was set on Far. I can't imagine how late it would be if it was on Near.
I think every owner with Uconnect knows, as good as it is, can be a little buggy. Where you set some checkmark and later go back in on something and it's unchecked. This was not the case here, but I've seen it in the past on my 2014 Limited.
Magically problems would disappear if I factory reset my 2014 Limited (without FCW). So I wanted to Factory Reset UConnect to see if that might help.
Bingo !! First test after a UConnect Factory Reset the FCW Warning with ACC off worked !!
I hate making a suggestion that could be complete nonsense and it could be. Is it a coincidence It worked on the VERY first trip out after I factory reset it? Possibly. But I doubt it.
Also be aware that I am better informed of the conditions to test it. Like prior tests maybe I had my foot slightly on the brake. Or I tested it below 20MPH. But it had gone off with ACC ON and engaged twice. But it was ACC that partly aggravated the encounter in the first place. I normally drive pretty lax.
Any way the situation to test it was nearly perfect. I had just washed it the day before by the way. Clear crisp morning.
Driving along at about 30-35MPH.
Up ahead was a Semi and Mercedes SUV behind it both stopped fairly hard. But I (my lax driving) was probably 15 car lengths behind. So this felt like a good situation to test it and I would not piss anyone off if I "zoomed" up to them (because they just stopped hard). Or cause an accident as nobody was behind me. I suspected since I had been riding behind the MB SUV it has already "tracked" it as a vehicle (as opposed to a stationary object).
So I just let it zoom in at 25MPH-ish and made sure not to touch the brake. And bingo the warning came up in plenty of time. And it didn't feel all that terribly risky.
I'll know for sure if the Factory Reset fixed it, if warnings come up now and then without "Testing".
Regardless I feel better that is seems to be working as designed.
I'll try to update this either way.
If it is indeed a UConnect glitch and Factory Reset fixed it. It's bit scary an "Infotainment" bug now IS a matter of life and death
Again this is NOT FACT, NOT LAB TESTED and just a hunch.