Anyone have this problem. Happened to me twice now, go to start truck and battery is low/dead to the point nothing comes on. Both times it I had a trailer connected overnight using just the 4pin connector. The first time I missed it was a low voltage because I got a message on the cluster stating "Park Brake Fault Service Now" That battery went down to 4V and I charged it up and everything is fine. Ford tested the battery and said it is ok.

 

Strange occurrence, I had a recent no start. Message center said parking brake only partly effective, service soon. Or something to that effect. I had towed a rental trailer with four pin the day before. Truck eventually started on the third try. No problem since.

 

I just purchased a new 2021 XLT last week. Let is sit for 72 hours, went to start it last night and it was completely dead. I made an appointment with the service dept. I have read their might be a phantom battery drain issue going on. I asked the advisor if their was a recall notice, she said not that she was aware of.

 

My dad had the same problems as y'all in his 21 xlt. Dealer said battery was bad and replaced it. Hasn't had any problems since.

 

I have a 2018 F150 with the same issue. I never had an issue until after I installed the in dash trailer brake controller. The battery was less than a year old. Drives & starts fine if driven every day. Battery slowly drains over time. If sits for a couple days to few days, Battery battery goes dead. Won’t start. Happened twice. Replaced my less than year old battery after the second time. It went dead again a couple months later. I notice the starter crank slower over time. Then after sitting a couple days or so. Dead again. I just pulled the fuse from the trailer brake pig tail and will wait and see what happens. Stay tuned…

Backstory…My F150 was one of the early 2018’s which did not have the pins installed on the fuse box for a trailer brake controller. I added the in dash trailer brake controller myself. Only to find it doesn’t have power from the battery. When I learned I could not install a fuse, I Added a pig tail on the fuse box on an open lug with a nut and washer. Put the wire through a grommet on the firewall located the trailer brake power lead under the dash. Cut and spliced the wire to my pigtail with a 20 amp fuse. Turned on the in dash trailer brake function with forescan & the brakes worked. The message center always gave me a “trailer brake module fault” when starting the truck. Whether using a trailer or not. But the trailer brakes work fine when used. I am suspecting the trailer brakes is the source of my issue because it only happened after installing the in dash controller. It really sucks to buy a new truck and find out a couple years later you can’t tow a trailer because Ford went cheap on the fuse box. I am not sure how to permanently fix this issue and still be able to tow a trailer.

 

You own a different generation F150.

 

Mine did this last month. Drove it to work....time to leave and it was dead...barely unlocked the doors. Called ERS and they gave me a jump and have had no issues since. It was weird. It wasn't even a super cold day or anything and I don't believe I left anything on.

 

My 21’ F150 has 17k miles goes dead if it sits for 3 days. Ford pass stops working often. Battery has been changed twice. 2 different dealerships have looked at it 6 visits, 20 days total. still without my truck.

 

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It is a very simple matter to test the current drain with the hood up and engine off.
If you have a Digital voltmeter, test from the >>Neg battery post<< to the >>chassis ground cable point connection<<.
By doing this, you are measuring the same voltage across the sample résistance the BMS does.
The sensor resistance value has to be known to be able to calculate the total power in watts that is being drained if it has any value to you. Power = I squared times R.
The total Current (I) is able to be calculated.
Current (I) = Voltage (E) divided by (R) the sensor resistance.
The above calculations are what is called OHMS LAW for electrical circuits.
If that Current is greater than about 1/2 amp, there is an excess drain to be looked for and the cause.
A half amp out of a fully charged H6 size AGM should allow the engine to started several weeks after the last time the engine was stopped.
After all, cranking drains as much as 100 amps from the Battery for a few seconds such that 1/2 amp is not much over a reasonable time interval when at rest..
Think about all the vehicles on a dealer lot. Do all the ones that have not been driven have dead batteries?
Sometimes when you pass a dealer lot, you may see someone with a lot vehicle, hoods up, jump starting those that have sat too long.
Its just a fact of life with these machines where a Battery has to keep the system alive in order to function when needed.
When you don't eat for a couple weeks you don't work very well either.

 

Thanks for the explanation of basic electricity. This is well past that and has challenged two different Ford dealerships to date.