Parking brake stuck on and light flashing

[Spiffy]

It's cold! Just now I went to start truck and battery was completely dead. I forgot to unplug a vlc from the obd port.
So I used my key to open door, got 40amp charger started. Truck did all sorts of goofy stuff. Mirrors went in and out. Horn hooking strangely, lots relays making clicks. Then I heard the parking brake engage. But dash message said breaks off.
I started the truck and everything seems fine but the parking brake light is flashing and the release won't work.
Any ideas?

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[Goldeneye36]

Is the brake actually on? Have you tried driving it? According to my '24 manual if the battery is dead the only way to release the parking brake is to hook up a battery booster and charge it up. A flashing light means it needs service. The low voltage must be making it act up. If you haven't already try letting the battery charge up for a bit then try again.

 

[Spiffy]

No I haven't tried to drive it yet. I assumed it was on because I heard the distinctive sound it makes when it engaged. Now if I try to engage or disengage nothing happens.
I do have a quite capable diagnostic tool that goes deep into the brake system.

I was worried that when I hooked up the 40amp booster there was a huge load. Battery was at 3.5 volts so no resistance. I was worried I had shot some erroneous current though the module.
Once I had this same brake issue after boinking things up in fdrs that I had to get help from Jesse.
He tapped in and the mouse went so fast I couldn't follow. He got things working.

I just put the new AGM battery in. Did I kill it by letting it get to 3 volts?

 

[Spiffy]

I tried to drive it. Was stuck. Hooked up my topdon diagnostic tool. Read the dlc . About half of the modules showed several codes including the abs. Most were from low voltage issues.
Cleared out the codes. 2 on the abs continued.
Right brake applied and left brake applied. Read the data stream and saw that the button was working. Left front and right front brake actuator applied.
Abs system checked out. Had a problem with the parking brake. Went to electronic parking brake service tools. Tried parking brake mantance mode. Figured that would pull the calipers back for a pad change. No dice. Tried to release the left actuator and then left. Still no go.
Finally I selected release parking brake. That pulled them back.
I was able to move then they locked up again.

Re read codes
PSCM lost communication with anti lock, invalid data with abs.
SOBDMC. Brake sensor A range/performance.
Other stupid stuff in ABS.
Ipma. Mitigation from emergency braking
PSCM Invalid data from ABS.

I could clear them with no dtc. But they come back .

Data stream looks good, all 111 data points are good. All 230 abs tests come back as normal.
So. I think the ABS has corrupt data. I think it got hit by unfiltered voltage but it's passing all tests. I'm going to do a pmi when my battery has returned to normal and I'm not hooked up to this dirty shop charger.

Does ford keep records of all this on their servers?

 

[Goldeneye36]

Your knowledge of this stuff is way beyond mine and it sounds like you turned almost every stone there is to turn. Hope you can get it working.

 

[Spiffy]

I got it working.

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