Stop Safely Now on start

[Ry2023]

I have had this same issue … happened to me twice but …. It hasn’t happened since …and that was two years ago…. But I have noticed both times it was doing an update……

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[AlaskaFlash]

I have not had that issue, but there have been a lot of issues with the 12V battery running low.
When the 12V battery gets low, "funny" things can happen and the other message SSN could have been a result of the low battery causing a sensor or test routine to error out and give the SSN.

According to the AI search (for what it is worth):

"Full accessory power active" means the vehicle's electrical system is on, allowing use of accessories like the radio and power windows, but the engine is not running. This state is usually achieved by pressing the start button twice without depressing the brake pedal. While it indicates the battery is functional enough to power these features, a continued message of "full accessory power active" when the car won't start can signal a problem with the battery, electrical system, or software, requiring a manual reset or professional diagnosis."

It then refers to this youtube video which seems to be your situation where the truck wouldn't start at first after getting the messages:



Your best bet is:
1) don't use the Accessory mode and
2) plug the truck in every night which should keep the 12V battery at a higher state of charge, and it will keep it warm if it gets cold (below 40F) at night up there in Alaska.

Another issue you could have if the battery gets low is over the air updates may not install.
One of those recently improved the routine that keeps the 12V battery charged so it should not fall as low.

Quite a number of owners seem to get the 12V battery replaced under warranty due to charging issues which let it get below 50% soc which can shorten the lifespan of AGM batteries.

Good luck!

Thanks for this informative reply. When this happened, the 12 Volt red battery icon was also lit, so, I think this may have been the issue. I have driven the truck numerous times every day since last Thursday when this happened without any problems.

 

[chl]

Thanks for this informative reply. When this happened, the 12 Volt red battery icon was also lit, so, I think this may have been the issue. I have driven the truck numerous times every day since last Thursday when this happened without any problems.

Glad to hear it's working now.

According to the customer service folks when my 12V battery got low last summer and OTA updates were stalled, they told me to drive around for at least an hour to charge up the battery - that didn't work to get the SOC up enough for the OTA updates (somewhere over 80%), so I saw a post on this forum about plugging into the EVSE and charging overnight and that did the trick.

The 12V battery has caused quite a few problems based on forum reports anyway.

It seems to be the weakest link - nothing will work right or even at all with a low 12V battery - strange they couldn't have done a better job with it since the HV battery holds so much capacity. Go figure.

 

[CD4TNF]

Hope that never happens again, next time just hit the remote climate start, let it run .... 5 to 30 minutes based on your settings, that should help recover some of the charge on the LVB until you could get to the truck.

Ohh clever. Good idea. I'll keep that in mind as a emergency trick.

 

[rdt7]

The truck would not start and gave the message "Stop Safely Now", and then "Full accessory power active". After turning the truck off and back on several times, it finally started.

This exact same scenario happened to me yesterday on my 2023 Lariat. I've only had it since May and this is the first issue I've had. It really shakes my confidence in the vehicle.

 

[NW Ontario Ford Lightning]

Considering the issues with low 12v SOC especially for those of us with "real winter" half the year...has anyone looked at using a larger capacity 12v battery? or even connecting two in parallel?

 

[Heliian]

Considering the issues with low 12v SOC especially for those of us with "real winter" half the year...has anyone looked at using a larger capacity 12v battery? or even connecting two in parallel?

No, it's fine. When it gets cold, say consistently below 5-10degC, I plug my truck in nightly. 3 winters in sudbury and no problems.
Some things about my vehicle:

-Never have any dongles plugged into the obd port or aftermarket acc. drawing power.

-I drive 25km each way to work 5 days a week, that's 40minutes minimum per day that the battery is getting charged by the truck.

-plugged in after 7pm in the winter to maintain battery temp regardless of soc.

-usually have a small jump pack with me, not only for me but since the lightning shouldn't jump vehicles, it gets other people going.

I've never had a problem, one day the 12v will lose its capacity and I'll replace it, just like every other vehicle I've ever owned.

 

[NW Ontario Ford Lightning]

Good to hear.
I bought my truck in January 2025 so had a bit of winter experience.
I park in an open car-port where my charger is set up. I plug in as soon as I get in each day and leave it plugged in until I am about to drive away again the next day.
I set up the Departure Times,
The cabin prepared on scheduled departure times is Awesome during some -30's stuff gotta say.
And since it is just electricity - so much cheaper than remote starting the 2500 Ram to warm up in that kind of temperature.

 

[pja3668]

My 2023 XLT SR with 35k miles has been at my local dealership for a month. The last day I drove it I had charged to 100 percent. I had a day full of errands to run. It started with a visit to the vet. My 8 year old tagged along and we stopped at his school playground on the way home for him to play for a few minutes. When we tried to leave I got the Stop safely now message. After towing it to the dealership and sitting for a week they said it was the gear shift module. Seemed odd to me that that would be it. Took a while but when they got the part and installed it sure enough that wasn’t it. They last claimed Ford needs to “push something” to it. All BS I think. I’m not sure what it is but it has me thinking I’m done with this truck. I’m almost out of warranty and wary of having issues like this down the line. *besides the fact that I borrowed a car for almost two weeks before they had a loaner. I just want my damn truck back. The longer and harder it is to diagnose this makes me more and more hesitant to keep it.

I should add. I’ve had numerous incidents where I had to disconnect the negative battery cable to reset the truck. This latest issue would not clear after several times disconnecting the battery cable. I had one incident that I had the whole family in the truck, we had just put our 15 year old dog down and were on our way home on the Garden State Parkway (an 80-85 mph road, if you’re not familiar) when the truck gave me the Stop Vehicle now message. I disconnected the battery and everything restarted fine. I hate to think it or say it but I might have met my limit. *it is an odd occurrence that both of the above mentioned issues happened on days I went to the vet.

 

[rdt7]

I had my first "Stop Vehicle Now" message (and forced stop). It occurred after I had been driving for about 15 minutes in One-Pedal mode. At a stop sign, I turned One-Pedal off and the warning popped up right after that. It was resolved by turning the vehicle off and back on again. As someone said, my confidence in the vehicle has been shaken. As of now, if this happens again, all I know to do is: 1) Turn vehicle off and back on, maybe several times, to see if it resolves. If not, 2) Remove and replace the negative battery cable. 3) Charge the 12V battery using the terminals in the frunk.

Is there anything else I should add to my checklist? And one final question: at what point would I take it to a dealership (hoping not to wait until it needs to be towed in)?

 

[B177y]

I had my first "Stop Vehicle Now" message (and forced stop). It occurred after I had been driving for about 15 minutes in One-Pedal mode. At a stop sign, I turned One-Pedal off and the warning popped up right after that. It was resolved by turning the vehicle off and back on again. As someone said, my confidence in the vehicle has been shaken. As of now, if this happens again, all I know to do is: 1) Turn vehicle off and back on, maybe several times, to see if it resolves. If not, 2) Remove and replace the negative battery cable. 3) Charge the 12V battery using the terminals in the frunk.

Is there anything else I should add to my checklist? And one final question: at what point would I take it to a dealership (hoping not to wait until it needs to be towed in)?

I'd take it to the dealer now to have them check codes and get the problem logged or fixed if there's any codes that point them towards something. Depending on your mileage, a 2023 should still be under warranty. Even if they can't find anything, if you get the complaint "logged" now and it happens again, you'll have the issue listed in the service records to help support your case.

 

[TaxmanHog]

It occurred after I had been driving for about 15 minutes in One-Pedal mode. At a stop sign, I turned One-Pedal off and the warning popped up right after that.

Why did you switch it off at that point and time?

Maybe a few of us can test this routine to see if it's a repeatable system wide issue or unique to your truck, I'll test on mine in the morning.

 

[rdt7]

Why did you switch it off at that point and time?

Maybe a few of us can test this routine to see if it's a repeatable system wide issue or unique to your truck, I'll test on mine in the morning.

I switched off then because I had just finished descending a mountain with a lot of switchbacks. After the stop sign, the road leveled out so I switched off one-pedal.

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