PCM reflash for corrupt file?

[PsycOhm]

Hello everyone! This is my first post on this forum.

I believe I have an unusual issue with my 2021 ST.

To preface this, I'm relatively familiar with auto mechanics but not a mechanic whatsoever.

So yesterday my A/C stopped working. Leading up to yesterday- I had super cold air, no unusual function of the compressor (rapid on/off or weird sounds from under the hood).

And now today, nothing. The compressor stopped engaging the clutch. Ok, so I went into my scanner to see if there was something inhibiting it from turning on (ie. temp sensor etc.) and I found nothing. So, as I am not a mechanic my next step was to check the Hi and Low side to see if it had leaked. That is where my diagnosis ended as it made more sense to hire someone to come out and run their own diagnostics.

The mechanic came out and was able to conclude the system did not have a leak, but though his troubleshooting, he concluded that there was a corrupt file on the PCM! His inability to be able to see the status of the compressor led him to look into the computer and see if it was commanding the compressor on. Thats where he saw that there was some kind of discrepancy, and it wouldn't allow him to see the activity through the PCM. His diagnosis was that the PCM needed to be reflashed and updated to correct the problem.

I'm sure I can do a better job of explaining this, but its a little challenging for me my apologies.

So, I guess my question is, has anyone had a similar issue? I'm not entirely sure how to go about correcting this. Any help is greatly appreciated.

Thank you!

EDIT- 30,426 miles and no modifications

 

[Polizi212]

I am not aware of a PCM reflash tool, but if he is not able to find and communicate with the Compressor sounds like it has lost a data connection. Any Check Engine lights or codes pulled from either scan? could be a data connection to the PCM or a bad PCM Might want to see if anyone else chimes in or just take it to Ford and let them diagnose it!

 

[PsycOhm]

I am not aware of a PCM reflash tool, but if he is not able to find and communicate with the Compressor sounds like it has lost a data connection. Any Check Engine lights or codes pulled from either scan? could be a data connection to the PCM or a bad PCM Might want to see if anyone else chimes in or just take it to Ford and let them diagnose it!

To answer your question, no there was no CEL or DTC present. I did notice this afternoon when I was working on it, there was a fault with the ABS module. There was an issue with the pump motor control, battery voltage, and lost communication with instrument panel cluster control module.

EDIT- I also observed that the freeze frame from the ABS fault event had recorded the external temperature sensor reading 415* F. I believe that this is also around when the A/C stopped working. (I don't think it takes a mechanic to know it was nowhere near that temperature anywhere in or around the car).

Coincidence? I have no idea, but that was something that I had observed.

I believe my next step should be to take it to Ford for a PCM update.

 

[Polizi212]

Losing communication could be a wiring issue. Perhaps rodents have entered the vehicle and gnawed on wires. or there is corrosion on the connectors. if you were in the great white north I would suspect corrosion. West coast I suspect could be either. a thorough inspection for chewed wires under the hood where you can just to see if any were damaged might be in order! Also did you check fuses for the AC system?

 

[PsycOhm]

Losing communication could be a wiring issue. Perhaps rodents have entered the vehicle and gnawed on wires. or there is corrosion on the connectors. if you were in the great white north I would suspect corrosion. West coast I suspect could be either. a thorough inspection for chewed wires under the hood where you can just to see if any were damaged might be in order! Also did you check fuses for the AC system?

Well I suppose that I have more that one issue at hand here...

In hindsight, I had noticed that an ABS fault had been stored in the past.. I got a CEL for the purge canister solenoid valve which I replaced about 2 months ago, but I saw the ABS issue and just cleared it not thinking anything of it (I chocked it up as it was "just a ford thing").

Guess I should have looked into that further. A wire problem seems like the only likely cause of this. hm..

My location isnt prone to rodents, but we did buy it from a dealership in Texas and I believe that it was originally purchased in Florida..

Now that I am thinking a little further into this, I am beginning to think that a reflash of the PCM may be a solution to a symptom and not necessarily the bigger problem at hand.

EDIT #3- Yes, all fuses have continuity.

EDIT #4- Now that I've looked through some wiring diagrams through Mitchell, the ABS module is connected to the HVAC system through the auto start/stop (to turn the A/C off during auto stop conditions)..

 

[Polizi212]

Now to figure out why you lost communication with the PCM. Is the Battery old? I have seen Battery voltage is very critical for these Vehicles. I would hand it over to a good Mechanic / tech that can trace down this issue!

 

[PsycOhm]

Now to figure out why you lost communication with the PCM. Is the Battery old? I have seen Battery voltage is very critical for these Vehicles. I would hand it over to a good Mechanic / tech that can trace down this issue!

So, I followed a flow chart on Mitchell and the first problem it said was to do exactly what you said. First diagnose the U3003:16 code which is for the battery voltage before moving to another step diagnosing the other two codes.

Once again, "in hindsight" I have been getting notifications on Ford Pass that "Some features have been disabled" due to undervoltage of the battery... That issue has been intermittent so foolishly I have brushed it off.

I believe that it is an original battery from the factory BUT I have not yet observed its condition. The reason for that is that I also have 2 other explorers (2005 sport and 2017 sport) and the 17 had an original battery which crapped out just after the 7 years it was designed for. With that in mind, I assumed that it was some faulty sensor in the ST that was causing that since the car is barely 4 years old.

Tracing an electrical problem with a diagram of how it is ran shouldn't be a major task for me to take on as I have 20 years of experience in the electrical field.

Thank you for your responses as they have given me some clarity. I tend to overthink problems and like some famous philosopher had once said that the most complex problems have the most simple solutions.

Cant wait to get to the bottom of this!!

 

[Dale5403]

A simple way to see if it is the battery is to put a slow charger on it for a day. Many have had battery issues before 4 years.

 

[Polizi212]

So, I followed a flow chart on Mitchell and the first problem it said was to do exactly what you said. First diagnose the U3003:16 code which is for the battery voltage before moving to another step diagnosing the other two codes.

Once again, "in hindsight" I have been getting notifications on Ford Pass that "Some features have been disabled" due to undervoltage of the battery... That issue has been intermittent so foolishly I have brushed it off.

I believe that it is an original battery from the factory BUT I have not yet observed its condition. The reason for that is that I also have 2 other explorers (2005 sport and 2017 sport) and the 17 had an original battery which crapped out just after the 7 years it was designed for. With that in mind, I assumed that it was some faulty sensor in the ST that was causing that since the car is barely 4 years old.

Tracing an electrical problem with a diagram of how it is ran shouldn't be a major task for me to take on as I have 20 years of experience in the electrical field.

Thank you for your responses as they have given me some clarity. I tend to overthink problems and like some famous philosopher had once said that the most complex problems have the most simple solutions.

Cant wait to get to the bottom of this!!

I would get that battery properly tested or Replaced. I would assume its bad. Batteries are an ounce of prevention worth a pound of Cure! see if that perhaps corrects some if not all issues. I always consider Batteries and Tires as item that the Manufacture will cheap out on. and my experience has been neither have made it long!

 

[PsycOhm]

Go figure! I went out to check the battery situation and this notification came up on my Ford Pass! Imagine that...

Yes, tomorrow I will be taking that to get checked out and probably replaced.

Crazy to think that my main issue could have stemmed from such a silly problem.

Every replacement part I use is Motorcraft. Period. I have this long standing belief that OEM parts are the best and most of the time only parts to use. I believe that blind faith has lead me into the position I am in now.

I also believe that Ford produces an amazing product (which is why majority of my immediate and extended family drive them). But I also think that Covid had something to do with some unusual phenomenon with vehicles produced during and after 2020.

Thank you guys for following along with this. I appreciate your suggestive input as it has helped me out tremendously.

I will follow up with the resolution, hopefully a replacement battery and an update to the PCM will resolve this.

 

[Polizi212]

My car once went into battery saver mode but that's because I left the interior lights on all night, my fault. A few hours on a charger and good to go. I usually always use motor craft parts. Your right COVID had a negative effect on builds across all manufacturers. I replace my batteries with interstate as they seem to really hold up and through Costco not too bad of a price. But everyone has a preferred brand. I look forward to seeing if the battery is your problem. I hope that's all it is!

 

[PsycOhm]

My car once went into battery saver mode but that's because I left the interior lights on all night, my fault. A few hours on a charger and good to go. I usually always use motor craft parts. Your right COVID had a negative effect on builds across all manufacturers. I replace my batteries with interstate as they seem to really hold up and through Costco not too bad of a price. But everyone has a preferred brand. I look forward to seeing if the battery is your problem. I hope that's all it is!

I don't have any personal experience with Interstate but I have heard good things.

I think that I will go with MotorCraft for the replacement if need be. Ford always stands by the products I buy from them, and if something doesn't work out, then at least they are the people receiving feedback from their products thus hopefully improving them.

I hope thats all it is too!! Thanks again

 

[ButchsExplorerST]

I had a very bad experience with Autozone agm battery. After installation and tested, work for 2 weeks then cause a direct short which shut off my vehicle while driving, scary as hell. Once tow into Ford Dealership only problem found was a shorted battery. Driving 1 1/2 months now no issues.