Random Accessory Mode

[mwalker1544]

Hey I have a Mustang GT that randomly puts itself in Accessory Mode. I get a run power active message and the engine shuts down. This has happened 3 different times and the dealership has been unable to replicate it.

Has anyone ever seen this before?

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[Rambl3r]

Hey I have a Mustang GT that randomly puts itself in Accessory Mode. I get a run power active message and the engine shuts down. This has happened 3 different times and the dealership has been unable to replicate it.

Has anyone ever seen this before?

Bump.. this just happened to me this morning in traffic. I thought it was user error at first but looking back, I'm pretty sure it wasn't me. Did you find out what this was?

 

[hideousorange]

Same thing happened to me this morning. Didn't even feel the car stall. It started right back up. Has it happened to anyone again?

 

[Rambl3r]

Same thing happened to me this morning. Didn't even feel the car stall. It started right back up. Has it happened to anyone again?

Not since the last time I posted. A little less than a month ago. I still dont know what it is :shrug:

 

[JackBauer]

did the car just shut off? if so it might be the throttle body issue that some are having. mine did that once, i was stopping at a light and the car just shut off with the power button light flashing and run power active.( haven't gone to the dealer yet for it...tsk tsk)

the throttle body/position sensor has been revised to fix this issue, and i believe the ecu also needs an update.

 

[Rambl3r]

did the car just shut off? if so it might be the throttle body issue that some are having. mine did that once, i was stopping at a light and the car just shut off with the power button light flashing and run power active.( haven't gone to the dealer yet for it...tsk tsk)

the throttle body/position sensor has been revised to fixed this issue, and i believe the ecu also needs an update.

Thanks! It shut off and it didn't feel like a stall. This sounds like it could be it. Going to have to take it in.

 

[Toretto]

bumping this thread...i'm taking the car in to the dealership this wed for them to check it out. Same exact issue as explained by everyone here - any updates?

 

[Toretto]

Quick update....after my KAM reset back in August 2021, car ran without any random shutdown (my 'stang is my daily driver) until earlier today, it happened as I was slowing down to a stop sign. Pretty cheesed as I thought this issue was behind me =(

Another thing to note, despite not having the car shut down on me for almost 8 months, I do notice that from time to time, while i'm driving, a "no key detected" message would pop up (and yes of course, my key is with me in the car), which makes me think, any chance this issue could be linked to the key fobs?

 

[Vlad Soare]

In one and a half years of daily driving it happened to me twice. Both times while I was stopped at a traffic light; never while driving. It didn't happen while I was already stationary, but right at the end of the braking phase, the very instant that the car came to a halt. It didn't stall; it didn't feel like stalling. It died so smoothly and quietly, as if I had pressed the stop button myself, that the first time I didn't even notice it wasn't running anymore until the green light came on and I lifted the clutch and nothing happened. The second time I saw the "accessory power active" message and didn't understand why, I thought it was some software bug, until I finally realized that the engine wasn't running anymore.

The no key detected thing is an old bug that plagues the entire Ford lineup, not just the Mustang. It's been with us ever since Ford introduced the keyless start system, and I really doubt they'll ever fix it. In fact I doubt they even consider it a bug. All you'll hear from them, or from the internet for that matter, is that the key battery is low and must be replaced. Sometimes it is indeed the battery, but not always. It does it with new batteries, too.
Occasionally you'll also see the message "restart now or key is needed" as soon as you turn the engine off. It's the same thing - key not detected.

 

[Toretto]

In one and a half years of daily driving it happened to me twice. Both times while I was stopped at a traffic light; never while driving. It didn't happen while I was already stationary, but right at the end of the braking phase, the very instant that the car came to a halt. It didn't stall; it didn't feel like stalling. It died so smoothly and quietly, as if I had pressed the stop button myself, that the first time I didn't even notice it wasn't running anymore until the green light came on and I lifted the clutch and nothing happened. The second time I saw the "accessory power active" message and didn't understand why, I thought it was some software bug, until I finally realized that the engine wasn't running anymore.

The no key detected thing is an old bug that plagues the entire Ford lineup, not just the Mustang. It's been with us ever since Ford introduced the keyless start system, and I really doubt they'll ever fix it. In fact I doubt they even consider it a bug. All you'll hear from them, or from the internet for that matter, is that the key battery is low and must be replaced. Sometimes it is indeed the battery, but not always. It does it with new batteries, too.
Occasionally you'll also see the message "restart now or key is needed" as soon as you turn the engine off. It's the same thing - key not detected.

The way you described the car turning off gracefully is exactly how it happens to mine. I guess you never went to the dealership to look for a fix/resolution eh?

As for the no key detected issue, that's fair and I'm not overly concerned. It's just strange as my '17 ecoboost premium never had that issue, not once.

 

[Vlad Soare]

I guess you never went to the dealership to look for a fix/resolution eh?

No, because it happens very rarely and I can't reproduce it. And there are no other symptoms and no DTCs. There's nothing I can show them. I'm sure they'd just send me off.

 

[Toretto]

No, because it happens very rarely and I can't reproduce it. And there are no other symptoms and no DTCs. There's nothing I can show them. I'm sure they'd just send me off.

This is true - happened to me the two times I brought it to the dealership. I will call them today though as somebody had posted a TSB that now applies to all S550 (2015-2021) - TSB SSM 50067 is the number I believe.

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