Auto Start/Stop Only Functions Intermittently

[GRB1959]

I took delivery of my 2024 Ford Bronco Badlands on Feb. 1, 2024. Up until now everything has worked perfectly on it. Just the other day the auto start/stop feature has begun to act up a bit as the feature is now only functioning intermittently.

I know that many folks on this forum have disabled this auto start/stop feature through various means, but believe it or not I actually like the feature and want the feature to function as designed. Attached are a couple of screen shots of the instrument cluster of my Bronco when the feature is not working.

I connected my Noco Genius 10 battery charger and when it was finished charging the battery was at 12.8V. So I took it out for a good long drive of 35-40 miles or so today around town and the auto start/stop feature was still not working. After running a couple of errands the auto start/stop feature started to function again and then when I got home it stopped working again. I am not sure what would cause this type of intermittent behavior. Perhaps a bad connector somewhere or a faulty computer module or perhaps the battery is defective?

When I got home my battery measured at 12.4V so are my voltage readings normal for this battery? It is sort of ironic that I want this feature to function as designed and I see many threads on this forum where Bronco owners are trying to disable this feature.

Any ideas, otherwise it will be an appointment with a Ford dealership to let them sort it out.

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[RagnarKon]

It's all normal.

There is a battery management system on the Bronco that keeps track of the health of the battery. If that system detects the battery level is too low, or if your accessory power draw is too high, it will prevent Auto Start/Stop from activating.

 

[Ducati1098]

@RagnarKon is right
There are many conditions required for auto/start stop to work, not only just battery voltage. It isn’t going to work or come on at every stop.
If something was wrong it wouldn’t work ever.

 

[GRB1959]

Thanks @RagnarKon and @Ducati1098 for your expertise. I just noticed the past day or so that the auto start/stop feature wasn't working all the time and was somewhat intermittent so I thought that something may be wrong with it.

 

[buck_6G]

It's all normal.

There is a battery management system on the Bronco that keeps track of the health of the battery. If that system detects the battery level is too low, or if your accessory power draw is too high, it will prevent Auto Start/Stop from activating.

I've had this exact issue, although with a brand new battery, the AC off, and nothing plugged into the cigarette lighter / USB / AC ports. It happens for weeks at a time, and recently has been happening when I remove the doors, but didn't always.

Drives me mad, because I don't want to be sipping gas at stop lights while driving around town.

It would be neat if the dashboard was able to clarify the conditions causing the auto start/stop system to disengage.

 

[WheresMyBronco]

I've had this exact issue, although with a brand new battery, the AC off, and nothing plugged into the cigarette lighter / USB / AC ports. It happens for weeks at a time, and recently has been happening when I remove the doors, but didn't always.

Drives me mad, because I don't want to be sipping gas at stop lights while driving around town.

It would be neat if the dashboard was able to clarify the conditions causing the auto start/stop system to disengage.

I believe the manual has details on when it should/shouldn't engage but I don't remember exactly what they are

 

[Tricky Mike]

I went through the entire winter without a single stop/start. Now that it's consistently above 50 it's back to normal.

 

[GRB1959]

I believe the manual has details on when it should/shouldn't engage but I don't remember exactly what they are

Good call, I just found this in the owner's manual regarding auto start/stop.

 

[HotdogThud]

@RagnarKon is right
There are many conditions required for auto/start stop to work, not only just battery voltage. It isn’t going to work or come on at every stop.
If something was wrong it wouldn’t work ever.

Noticed this recently too, so maybe you can confirm. I think the logic behind the ASS (giggle) got updated recently and more factors have to come into play for it to engage. When I first got my bronco that thing would kill itself at the stop sign at the end of my street with the engine still cold, every single time. Now, it doesn't seem to ever engage if the oil temp is below about 125 (which is good, IMO). My battery tests fine though all of this.

Things that I *know* are a factor include:

• Battery condition
• AC running or not
• heater running or not

I feel like the oil temp one might just be perception though. Bosch has put a lot of voodoo into those over the years

 

[Ducati1098]

Noticed this recently too, so maybe you can confirm. I think the logic behind the ASS (giggle) got updated recently and more factors have to come into play for it to engage. When I first got my bronco that thing would kill itself at the stop sign at the end of my street with the engine still cold, every single time. Now, it doesn't seem to ever engage if the oil temp is below about 125 (which is good, IMO). My battery tests fine though all of this.

Things that I *know* are a factor include:

• Battery condition
• AC running or not
• heater running or not

I feel like the oil temp one might just be perception though. Bosch has put a lot of voodoo into those over the years

This is what the workshop manual lists:

 

[Karl_in_Chicago]

Trust me, it's the state of the battery and the draws on it at the time. My '23 BL sits for weeks and I live in the heart of the City so it's all stop and go. When I first take it out the auto S/S is kept off with the same icon you see. When I do my monthly-ish run of a couple hours driving it will eventually pop back to the "normal" mode but often not until after I've actually stopped and turned the truck off. In any case I'm closing in on a year of ownership and that's how it's been working for me. FWIW I'm also fine with the standard auto S/S function, it's never interfered with my driving.

 

[HolidayDog]

I noticed today when I tap that ASS button it turns off Sirius radio.

I’ll try again tomorrow and see if I can reproduce the error.

 

[breaddrink]

Did you ever figure anything out or notice any change?

Mine started doing this very thing. The vehicle charging status instead of cutting the engine.

Seemed to coincide with the latest update. Roughly 2 weeks ago...

 

[Brian_B]

Put your battery on a charger overnight. Make sure to connect the charger "properly" (ground via chassis, not on the battery terminal post)

This will let the BMS system see the battery charge, and then the BMS will let your ASS resume ASSing.

This is common if you make a lot of short trips, or if you deep drained your battery one night, or it could be a sign of an aging battery. An update could feasibly do it, but it should eventually get back up to normal charge and resume ASSing.

If this doesn't fix it, you could have a battery on the way out. Watch out for repeated "deep sleep" notifications, which is the next "no, really, your battery is probably about to die" sign.

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