2023 Explorer ST fails to download bootloader??

[JohnBradley]

I was tuning a friend's ST and after we were done I went to turn off the dyno mode with a flash, it started failing to download bootloader. I thought it was an internet issue so I moved it to where we have good signal, started the flash and then it failed halfway thru. I can go anywhere from 21% to 90% and then I will get the x7F negative response code.

[04silverado6.0]

I have not had that happen. Please update with your solution.

[JohnBradley]

While I am still not 100% sure of the cause, the resolution was basically the only thing left to try after 2 hours of failed flash attempts. It had failed halfway thru a write and was then immobile as well as bricked more or less. With nothing left to lose, unhooked the battery for 10 minutes, made sure all power was gone by cycling the brake pedal, then hooked it back up and reflashed successfully. This very easily could have made it worse (least for most ECUs) but somehow worked in this case.

[JLawson240]

Make sure you're connected to the internet

[04silverado6.0]

That was my first thought was disconnecting the battery. Could have went either way.

[SlowSTExploder]

Whats up brotha, I had this happen to me the other day.. low voltage to the pcm is what I would assume happened and or HPs servers had a hiccup, mine also failed in the download boot loader stage, tried it again and got passed bootloader, into writing, and failed at 12%.

Took several attempts to reload the stock OS as it kept failing to write...

But once I got it to flash which was later in the day, it's been fine since.

[jakevandee]

I've had issues with some 2.7's & 3.0's and flashing after sitting for a little while. Battery charger did the trick. Never had a problem with 16 and prior cars. Current assumption is tight voltage thresholds, not exactly sure yet though.