ECU Failure

[TruckGal516]

Hi everyone,

Not sure if ECU is main issue but I’m hoping someone can point me in right direction. I have a 2021 Lariat and my issues started 2 weeks ago. First I was stopped at a light and all my screens went black and then after a few seconds came back on (as if someone had turned off and then turned back on the truck) because the truck hadn’t been in park the shifter flashed and then moved it self into park. This issue happened 2 more times on other days then happened again this weekend while I was driving. I lost all control of the vehicle (power steering etc) luckily I was going less than 5mph as I was turning into a driveway. Any clue as to what’s going on? Dropped at dealer today but they said they could have it for weeks before they figure out what’s wrong.


Thanks and apologies if this is in the wrong thread.

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[Snakebitten]

Doubt it's the ECU because your truck is really about 40 different modules.
I'm not sure exactly which module could trigger such an event but it sounds more like a possible power interruption?

Maybe a ground strap or main harness connector not assembled correctly?

 

[Pedaldude]

My first bet with any newer vehicles would be the battery. If all these modules aren’t seeing 12V at most times, all kinds of electronic gremlins will begin to appear.

I use one of these for quick diagnostics and to check battery health on startup:

Many have experienced loose connectors and crimped wires too.

Good luck!

 

[Viper]

Also check your under hood fuses for proper seating, a lot of people have had weird problems resolved (for the most part) by fully seating them.
Good luck, hope it is something simple!

 

[powerboatr]

Doubt it's the ECU because your truck is really about 40 different modules.
I'm not sure exactly which module could trigger such an event but it sounds more like a possible power interruption?

Maybe a ground strap or main harness connector not assembled correctly?

second a ground or harness issue
i had a f350 that would off at random times, 70 mpg or 0 didnt matter
turned out to be the ecm ground on drivers fender area....of course it was the one i used to ground some lights and it must have un-tightened itself.

have you done any under hood or battery terminal work

 

[SRHAGEN]

That’s very interesting. I found loose battery and fuses out of wack on my new 22 XLT just looking it over when new.
I always check that stuff. not my first new truck. Check lug nut torque (mine were all at under 100 lb ft ) spec is 150. Rotor screws exhaust clamps, body mounts etc. both my ws wipers are bad 1 ur 12000 mile warranty day one just smear. there is always something loose.
I can’t get over all the tape from assembly and rubber bands.

Also found if u open the door in drive it goes to park and will mess with the screen.
Trying to look at the ground with the door open when driving slowly shuts all down. Scary the first time. I was looking for a curd and it slammed into park. I had to cycle key to get everything working again. Any body else found this situation. Or how to avoid it.
I’ve often put my boat in, looking out the door for obstacles or when the rear tire hits the water. Not with this truck I guess.

 

[Snakebitten]

I think if your seat belt is fastened, you can open the door without the shifter going to Park.

 

[SRHAGEN]

I’ll try that, thanks. See, that’s awesome here I was thinking it was just the way it is. Somebody knew the answer. Too cool. Sometimes it so simple.

 

[Ford Motor Company]

Hi everyone,

Not sure if ECU is main issue but I’m hoping someone can point me in right direction. I have a 2021 Lariat and my issues started 2 weeks ago. First I was stopped at a light and all my screens went black and then after a few seconds came back on (as if someone had turned off and then turned back on the truck) because the truck hadn’t been in park the shifter flashed and then moved it self into park. This issue happened 2 more times on other days then happened again this weekend while I was driving. I lost all control of the vehicle (power steering etc) luckily I was going less than 5mph as I was turning into a driveway. Any clue as to what’s going on? Dropped at dealer today but they said they could have it for weeks before they figure out what’s wrong.


Thanks and apologies if this is in the wrong thread.

Good morning. Can you please send over a private message with your VIN and the name/location of your local Ford dealer? I would like to look into this on my end.

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