S650 Autostart start n stop how to disable this system for good

[danny58612]

Hello i own a 2026 Ford Mustang Eco-Boost I love it but it is a miss- build it doesnt contain the ASS button, and because of it custom mode can’t turn it off because i guess their interlocked with each other. So i run a car with this annoying Feature i dont want to turn off my BMS/ASS, because i live in cold place where i highly relay on it to keep my battery in check i forget to turn off lights all the time. CAN SOMEONE PLEASE HELP…. Also i cant tune it because i dont wanna void warranty and ford is dragging their toes on it i been in contact with my dealer for almost 2 months with out then still getting me the part.

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[jbrnigan]

Hello i own a 2026 Ford Mustang Eco-Boost I love it but it is a miss- build it doesnt contain the ASS button, and because of it custom mode can’t turn it off because i guess their interlocked with each other. So i run a car with this annoying Feature i dont want to turn off my BMS/ASS, because i live in cold place where i highly relay on it to keep my battery in check i forget to turn off lights all the time. CAN SOMEONE PLEASE HELP…. Also i cant tune it because i dont wanna void warranty and ford is dragging their toes on it i been in contact with my dealer for almost 2 months with out then still getting me the part.

Does you car not have the ASS button - first buitton just to the right of the start/stop switch? This is a picture of my 2026 Ecoboost .........

 

[danny58612]

Yes im missing its due to problem ford did i dont have that button its black on my most left side the one next to start engine stop switch

 

[DT-GT]

Wow! Wow! Wow! That is one major screw-up by Ford. I can’t imagine! I would be so pi$$ed! Hope they figure something out for you!

Yes im missing its due to problem ford did i dont have that button its black on my most left side the one next to start engine stop switch

 

[jbrnigan]

I'm just asking out of curisoty ... Does the car actually have ASS? Will it keep running if you auto / remote start? Does it actually shut off after stopping - in drive - foot on brake? Reason I ask, some rumors that Ford was going to disconnect ASS on some models....

 

[NegativeMultiplier]

Seconded the above question. Just to make 100% sure and not because we're questioning you, you do not have that button either physically or in the software, and yet you still have AS/S, and your engine does occasionally shut off when stopped, in gear, and you get the green "A" light at the bottom of your dash?

If yes, then as mentioned this is a huge mistake Ford has made, as I could be wrong but I'm fairly certain automakers are required to give users the ability to turn it off.

Though I'm more confused as to why you don't have the button in MyMustang, because SYNC should have been informed that the feature exists. Interesting.

 

[Kaptain75329]

Missing the Auto Start Stop button would indicate that the feature is not installed. It's possible Ford may have dropped the feature since it is no longer mandated, but that would be a pretty quick change; my 2026 GT has the button.

In any case, I don't think there's a way to disable Auto Start Stop permanently, it has to be disabled with each engine start. (No doubt this is why Ford put that disable switch right next to the main start button; the idea being you can start the car then disable right away.. basically a clever example of "malicious compliance" on Ford's part.)

Still, if somehow you do have Auto Start Stop yet are missing the disable switch, that seems like a visit to the dealer would be in order to have the problem corrected so you can get the switch installed. All EcoBoost Mustangs should have Auto Start Stop as standard; the GT models didn't get that feature until Job 2 for the 2024 model year.

In the meantime, one work around would be to drive in Sport mode which disables Start/Stop by default, and you could also create a custom drive mode in the Mustang menu: there's an option to disable Start/Stop in any drive mode you create.

EDIT: apologies for missing some details:

1) Looks like you did try to create a custom drive mode as a workaround, and that fails because of the possibility that the system requires the disable switch in order to honor your request for disable of Auto Start Stop.

2) Likewise, it looks like your dealer is aware this is an incorrect build and is waiting on the appropriate part to fix the problem.

With both of those points being true, there's nothing anyone here can do to help that you haven't already done yourself - unless there's someone here who works for Ford with enough influence to move the process faster, but even then it looks like the problem is actually with the part supplier, not Ford directly.

You've already done the right thing and contacted your dealer, who in turn is working with Ford to get the correct part that will allow for Auto Start Stop disable. The part is backordered and so even Ford can't do much until their supplier gets back on track. You will simply have to wait until the dealer gets the part and can effect a fix.

 

[Sofa King]

Engine Stop Start Eliminator for 2024 - 2026 Ford Mustang

They built the car wrong and need to fix it!

 

[danny58612]

I'm just asking out of curisoty ... Does the car actually have ASS? Will it keep running if you auto / remote start? Does it actually shut off after stopping - in drive - foot on brake? Reason I ask, some rumors that Ford was going to disconnect ASS on some models....

Yes it works

Missing the Auto Start Stop button would indicate that the feature is not installed. It's possible Ford may have dropped the feature since it is no longer mandated, but that would be a pretty quick change; my 2026 GT has the button.

In any case, I don't think there's a way to disable Auto Start Stop permanently, it has to be disabled with each engine start. (No doubt this is why Ford put that disable switch right next to the main start button; the idea being you can start the car then disable right away.. basically a clever example of "malicious compliance" on Ford's part.)

Still, if somehow you do have Auto Start Stop yet are missing the disable switch, that seems like a visit to the dealer would be in order to have the problem corrected so you can get the switch installed. All EcoBoost Mustangs should have Auto Start Stop as standard; the GT models didn't get that feature until Job 2 for the 2024 model year.

In the meantime, one work around would be to drive in Sport mode which disables Start/Stop by default, and you could also create a custom drive mode in the Mustang menu: there's an option to disable Start/Stop in any drive mode you create.

EDIT: apologies for missing some details:

1) Looks like you did try to create a custom drive mode as a workaround, and that fails because of the possibility that the system requires the disable switch in order to honor your request for disable of Auto Start Stop.

2) Likewise, it looks like your dealer is aware this is an incorrect build and is waiting on the appropriate part to fix the problem.

With both of those points being true, there's nothing anyone here can do to help that you haven't already done yourself - unless there's someone here who works for Ford with enough influence to move the process faster, but even then it looks like the problem is actually with the part supplier, not Ford directly.

You've already done the right thing and contacted your dealer, who in turn is working with Ford to get the correct part that will allow for Auto Start Stop disable. The part is backordered and so even Ford can't do much until their supplier gets back on track. You will simply have to wait until the dealer gets the part and can effect a fix.

no it shuts on and off on. Stop light and the A light with circle is on the corner of the cluster works just cant be controllerd
completely

 

[danny58612]

Seconded the above question. Just to make 100% sure and not because we're questioning you, you do not have that button either physically or in the software, and yet you still have AS/S, and your engine does occasionally shut off when stopped, in gear, and you get the green "A" light at the bottom of your dash?

If yes, then as mentioned this is a huge mistake Ford has made, as I could be wrong but I'm fairly certain automakers are required to give users the ability to turn it off.

Though I'm more confused as to why you don't have the button in MyMustang, because SYNC should have been informed that the feature exists. Interesting.

Its their you press off right and then go in custom mode but the car acts like nothing ever happened my guess it most light up “off“ near the light but since its not functioning the system can’t confirm itself its on or off so even if its switched off on drive mode it acts like its enabled

 

[danny58612]

I'm just asking out of curisoty ... Does the car actually have ASS? Will it keep running if you auto / remote start? Does it actually shut off after stopping - in drive - foot on brake? Reason I ask, some rumors that Ford was going to disconnect ASS on some models....

Yeah the logo is their you stop the engine speed Hits zero you let go of break it restarts

 

[danny58612]

DOES ANYONE PLEASE HAVE ANY AS BULIT DATA TO TRY TO TURN IT OFF BESIDES BMS :((((((

 

[jbrnigan]

The thing that puzzles me .... The fact that the switch is "blacked" out would seem to indicate that whoever supplies Ford with that switch and / or assembly, would have to have been notified by Ford to make that change. (an engineering change notice). Ford would have rejected a misprinted switch.


EDIT: I guess I'm confused ...Does your switch panel look EXACTLY like the picture I posted???

 

[danny58612]

The thing that puzzles me .... The fact that the switch is "blacked" out would seem to indicate that whoever supplies Ford with that switch and / or assembly, would have to have been notified by Ford to make that change. (an engineering change notice). Ford would have rejected a misprinted switch.

What do i do i have the system always active every time i stop the engine stop so i have to do rolling stops

 

[jbrnigan]

I'm confused ...Does your switch panel look EXACTLY like the picture I posted???

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