My first post so please forgive me if I do something incorrectly.

I'm having two intermittently recurring problems with my 2021 F150 XLT with 3.5 Ecoboost. Both issues seem to occur in close proximity when they do occur. My Ford dealer says no codes are displayed so they can't identify what the problem might be.

First issue - When driving, the three-tone warning will sound, but no warning lights appear on the dash. The tone is that of not having a seatbelt buckled or of opening the door with the key in the ignition. When this occurs, all belts are buckled in occupied seats and no extra belts are buckled.

Second issue - When trying to unlock the doors with the remote, there is no response. When then opening the door with the key, the pending alarm warning sounds and appears on the dash screen. Starting the engine cancels the warning and everything resets. No other warnings appear on the dash prior to or after starting the engine. New batteries were put in each remote but that did not prevent this problem from occuring.

The above issues do not occur at the same time but do seem to occur within a couple of days of one another. It seems like an electrical problem - maybe an issue with one of the control modules - but the dealer can't identify a problem since no codes appear. They advise to leave the truck with them so they can try to replicate the problems. They could try it multiple times a day and not have it occur over a period of two to three weeks, and I can't be without the truck for that long.

I'm looking for thoughts on what may be causing these problems.

 

On 1: I'd want to research the wiring diagram and look for electrical commonality between the open door and seat belt latches.

On 2, issue may be related to 1. Especially if both symptoms started at the same time.

extra thought, any modifications to the truck? Eg after market theft system added? Dealers typically hack those systems into the wiring harness.

 

Just a comment:
The Modules associated with those functions set U or B codes, not engine P codes.
All those modules can be diagnosed separately.
If the issue is present at that time, a code should be set.
Good luck.

 

Just a thought battery problem. I'm sure somebody with more experience with these trucks might chime it.

 

I haven't noticed those symptoms being mentioned for battery issues but these things do all kinds of odd stuff when the battery isn't quite right. How much of a pain would it be to put a charger on it when parked for the night for a month or so and see if that cures it?

 

Thanks for your thoughts. No mods that would affect anything electrical, just running boards (non-electric) and mud flaps.

 

Thanks for the information on the codes. I've asked the dealer's shop to scan the codes before I turn the truck off - doing so apparently clears the codes - but they say I have to schedule an appointment for them to do that work and of course the truck would be turned off before that could occur. It seems they are more interested in maximizing profits over ensuring customer satisfaction.

 

Do you have a package on a seat? Could be you hit a dip in the road and the inertia is enough to make the truck think the seat is occupied and not buckled.

 

Thank you for the thoughts. I believe it is related to an electrical issue. Based upon additional research I've done there are at least three TSBs that have been issued by Ford concerning a problem with parasitic battery drain on 2021 F150s. It seems the Ford mechanics should be aware of TSB 21-2097 (software update concerning the gateway module and door latch issues), and TSB 23-2130 (A/C clutch draw). There third TSB, concerns the PowerBoost engine, which mine is not.

There is no indication on either service invoice that any of these items were examined or tested. It seems that if there is no problem code indicated, the mechanics have no idea how to diagnose a problem. It is very disappointing that the customer has to identify potential causes for the mechanic. I'll have the truck back in the shop as soon as I can get an appointment so they can ensure everything related to the TSBs is examined and hopefully addressed.

 

Nothing on the unoccupied seats.