Got a doozy going on.
I have a 2017 super cab with the 2.7 Ecoboost. Last night the perimeter alarm went off at 2AM. Pushing the button on the key fob didn’t turn it off, so I started the truck and it stopped. 5 minutes later, the same thing happened! I’m sure my neighbors were hating this! Then it happened once again! I wound up unhooking the battery to get it to stop
This morning I went to hook the battery back up and the horn started blowing! I took that fuse out and it stopped. Imagine that
But now, when I turn the truck off, the radio and headlights won’t turn off! Turning them off manually is a no brainer, but now the 4-way flashers won’t stop! I swear that I’m not making this up! I had to disconnect the batttery again to get them to stop
Where do I start looking for an answer?

 

I would start with a new fresh battery.

 

Mice eating wires?

 

It took FOUR days, but my repair shop figured it out. Everything electrical was going haywire. Turns out there was fluid in the ECM housing! Seems that condensation can develop here depending on well it's insulated. They open the housing, wiped what they could then used a blow dryer on the rest. Everything is back to normal.