2020 F350 Lariat w/6.7L diesel.
About 4 years ago I replaced the headlights and front blinkers with LED's and disabled the bulb and LED outages with FORScan. Everything worked as it should and I had no hyperflash.
Fast forward to earlier this year when the passenger side rear skin, turn signal/brake light assembly w/BLIS and bumper section had to be replaced due to damage. It took the body shop three tries to finally get it right and after this i noticed that I had hyper flash on the driver side.
I went in to FORScan and checked and all settings I could find were still disabled in plain english and Hexadecimal. Front bulb turn outage, Front turn LED outage and ABM outage, I even disabled the rear turn LED outage.
I enabled the front bulb outage and got hyperflash on both sides. I disabled it again and hyperflash is gone on both sides. It will stay gone through power cycles/switch on and off, but as soon as I start the vehicle hyperflash returns on the driver side.
Enabling any of the bulb/LED outage settings and then disabling them again creates the same results. No hyperflash until I start the vehicle.
The batteries were replaced in November of 2023 and I unplugged all of the connectors I could find under the back of the truck and sprayed contact cleaner in them. The only one that seemed to have any connection to the tail/stop lights is a tan connector that goes to both sides. It is located on the passenger side frame rail by the spare tire. this had no effect.
As far as I can tell, all of the bulbs/LED's on the vehicle are working as they should.
Any ideas or suggestions of what to try would be welcome.
Thanks!

 

So the taillights are not LED?. If so check all four taillight bulbs on all functions stop turn and tail. Does a 20 have separate amber turn signals? I can’t remember. Anyway it’s common for one of the turn signals to be out but the tail still works. Hard to notice unless you can see it while it’s operating. Happened to me and sure enough top right was out on turn function only.

I’d learned on this forum to check that as lots have chased the hyper flash thinking the taillights were working and didn’t notice the flash function was not. Turned out to be a simple solution.

Double check especially if a body shop has had things apart.

 

I had a similar issue on my 2019 f350.
It looked like all my bulbs were fine but upon closer inspection some of them were dual element and one of those were bad.
After swapping some bulbs around I was able to locate the faulty one, replaced it and it’s as good as new.
Good luck.

 

Yes you do have to look close to see all bulbs and functions are working. If the 20+ trucks do have separate amber signals in believe a bad brake light bulb will also cause hyper flash.

 

Thanks for the directions, folks. Yes the 2020 does have the separate amber blinkers, and it is difficult to check all the bulbs by yourself. I finally managed it though!
The lower driver side brake filament was bad. Replaced the bulb, and viola, no more hyperflash!

 

Glad that you found your solution and posted. It may help someone else out in the future.