So, my 21 Lariat started behaving strangle last winter. The passenger side door handle unlock sensor quit working. Auto Start/Stop quit working (that was OK with me). The interior light wasn't coming on when I opened the door and it didn't flash the light sensing the presence of the key fob as I approached the truck. Also, the radio wouldn't keep playing after the engine was off like it did before. I think there was a couple more things that are escaping me.

So I took it in to the dealer (still under warranty) and said there were a number of possible causes, but will all that they thought it went into an electrical "limp mode" (my phrase) where features that are "unnecessary" are disabled because the truck detected a low battery situation. Apparently it saves the battery low point and, if it's below a certain level, limp mode is activated. I'd gone on vacation for two weeks and the truck sat unused and it seems the parasitic drain was enough to drain the battery enough to trigger it. They said once it happens, it has to be reset at the dealer (I'm guessing forscan would do it too).

Anyway, this was not at all what I suspected but I thought the info might help someone else down the road....

 

A battery tender should come with the trucks now a days!

 

i had battery issues on my 22 and it had the lesser of the specified batteries that should have been installed
dealer put in the correct battery and i used forscn to boost SOC level to 95%


battery size required



so far , now i only get low battery stuff if i dont drive for a week or so and open up truck alot to get stuff and running boards run down battery

 

Yeah this. It's be great if it wasn't needed, but ti seems to be the easiest way to avoid and solve problems.

 

My diesel trucks always had dual batteries. Maybe it's time we do the same. There's room under the hood for second battery.

 

So, the fix was bigger battery with more CCAs and change setting in Forscan?

 

yes for me

 

My truck’s OEM battery died at exactly 2 years. The replacement, an O’Reilly’s Super Start has lasted nearly 6 years now with no issues. The Motorcraft batteries seem to be hit or miss when it comes to longevity.