TSB 21-2097 : 2021 F-150 - Discharged Battery / No Crank

[unixadm]

TSB is attached.

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[JakeFlorida]

Randomly my truck would be unlocked more often than locked when I checked (no remote in my pocket). My truck also drained the battery one night down to 8V. After bringing the truck in, they reloaded all programs including new versions for lights/ windows. I have not had either issue since the software update. I also had an electric trailer brake module toast during this event. Part just came in and getting replaced this week. If you experienced the battery drain issue, you should definitely bring it in for a software update/ re-flash.

 

[Smitdog]

Randomly my truck would be unlocked more often than locked when I checked (no remote in my pocket). My truck also drained the battery one night down to 8V. After bringing the truck in, they reloaded all programs including new versions for lights/ windows. I have not had either issue since the software update. I also had an electric trailer brake module toast during this event. Part just came in and getting replaced this week. If you experienced the battery drain issue, you should definitely bring it in for a software update/ re-flash.

Do you know if they just reloaded programs, or specifically applied this TSB?

I just want to make sure the flash update is available before taking my truck in (I experienced dead battery after vehicle sat for 10 days).

Thanks...

 

[Smitdog]

So I had TSB 21-2097 applied at the dealership today. Only took 45 minutes. Time will tell if it prevents the battery from draining. Vehicle will soon be sitting for 5-6 days, will update after that time.

 

[King Ranch60]

Took mine to the dealership yesterday, waited for it and according to the service paperwork they found the TSB, did the the necessary download(according to the service writer) charged the battery. Now time to wait and see if it works.
(p.s. Thanks for the TSB pdf unixadm!)

 

[dtankman]

Is there anything like this about the 2018 XLT? I bought mine last Fall, and several times during the winter (in SC...so not really even that cold) I would get a message the remote features had been deactivated. I suspect it could also be due to a lower rated (CCA) battery that could cause it.

 

[unixadm]

Is there anything like this about the 2018 XLT? I bought mine last Fall, and several times during the winter (in SC...so not really even that cold) I would get a message the remote features had been deactivated. I suspect it could also be due to a lower rated (CCA) battery that could cause it.

Likely a bad/weak battery, along with needing the Battery Management System (BMS) reset. I had a 2018 Lariat and put a new battery in it a few months back from AutoZone (AGM). I also used Forscan to reset the BMS. No issues after that. My truck nearly left my stranded after a 45 minute drive, so I knew something was up. Previous to that I was getting the messages that you mention.

 

[Smitdog]

Left truck at airport for 6 days, started right up upon return, so assuming the TSB 21-2097 flash update fixed the battery drain issue.

 

[Airborne_Ape]

You can skip ahead to 3:37 in this video if you don't care much about the details.

But a rear door realignment was my solution. The door lock circuit works fine and the tail lights display the proper visual feedback, but the white exterior lighting would stay on because a door ajar circuit was preventing the BCM from putting other modules to sleep in the vehicle network.

I think that service providers telling owners to disable the 360 lighting is making troubleshooting more difficult. It's not the cause it's a side effect and frankly the only visual que that something is wrong.

The TSB has a door alignment listed as part of the solution and in both my 2016 and 2021 F150 it's the only solution necessary.

It makes me wonder what the software update part of this is? Did they put in a timer to automatically shut down modules, did they change the millisecond threshold of the door ajar circuit monitoring, or is it just an empty update to make people feel better about consumer electronics on wheels?

If anyone wants to jump into the deepend first, you can change the logic states in the BCM for the door ajar circuits at 726-32-01 and 726-34-01 as an advanced but very cost effective troubleshooting method.

Master 14 Gen F150 ForScan Thread:
14 Gen ForScan Thread

 

[Smitdog]

You can skip ahead to 3:37 in this video if you don't care much about the details.

But a rear door realignment was my solution. The door lock circuit works fine and the tail lights display the proper visual feedback, but the white exterior lighting would stay on because a door ajar circuit was preventing the BCM from putting other modules to sleep in the vehicle network.

I think that service providers telling owners to disable the 360 lighting is making troubleshooting more difficult. It's not the cause it's a side effect and frankly the only visual que that something is wrong.

The TSB has a door alignment listed as part of the solution and in both my 2016 and 2021 F150 it's the only solution necessary.

It makes me wonder what the software update part of this is? Did they put in a timer to automatically shut down modules, did they change the millisecond threshold of the door ajar circuit monitoring, or is it just an empty update to make people feel better about consumer electronics on wheels?

If anyone wants to jump into the deepend first, you can change the logic states in the BCM for the door ajar circuits at 726-32-01 and 726-34-01 as an advanced but very cost effective troubleshooting method.

Master 14 Gen F150 ForScan Thread:
14 Gen ForScan Thread

Excellent troubleshooting skills and explanation of your findings! Thank you for posting this info, and I would hope it makes it to all Ford F150 engineers and dealer technicians.