I recently bought a used 2015 F-150. My alarm system goes off when ever it wants to but before I can get the key fob, it turns it's self off. I tried re-shutting all the doors. All doors are locked with the key fob. It has 120k miles. Any ideas?

 

It could be the hood ajar switch starting to go bad. It is integral to the hood latch. Disconnect the electrical connector and use a short length of wire to short across the two terminals in harness side connector. If the problems disappears, then the switch is going bad. This is a reasonably common issue in the early Gen 13 trucks.

If you are in the truck when the alarm goes off there should be a message on the IPC telling you what triggered the alarm.

 

Do you think spraying it with WD 40 would help?

 

That has worked for some people.

 

My hood switch was gummed up with junk, it was stuck in the hood closed position, I sprayed it with solvent and it started moving again, but also now failed and started giving the alarm. I just put an entire new hood latch on which comes with a new switch.

 

My dad's 17 went off by itself a few times in the middle of the night. Took it back and turns out it was the hood latch.

 

Time to do some proper diagnostics to determine the source in your particular case. The truck's computer stores the last 4 causes for the alarm. Query the BCM for the ALARM_EVT pids. Forscan will do this. Here is the last 4 from my truck, and separate screenshot for possible sources. Our trucks do not monitor all of these sources.