Question on auto start/stop and battery condition

[jborbs]

Hey all - I noticed recently that my auto start/stop was no longer shutting off the truck (2021 F-150 Lariat 502a EcoBoost). Unlike many folks, I don’t mind this function and prefer it to be on. I hooked up my laptop with FORScan and monitored all of the SS_INHIB metrics and found that the one which seems to be consistently stopping the start/stop from activating is SS_INHIB_G2_08, which corresponds to battery management (i.e. low power)

The truck is showing 14+ volts at all times while driving, it fluctuates of course.

I’m trying to figure out if this means I should be replacing the battery. I believe it’s from the factory, I’m the second owner and there are no date codes I can see on the battery, but it is FoMoCo OEM.

Anything I should be checking more specifically? The measurement intricacies of AGM batteries are a lot to get my head around so I’m not even really sure how to tell if the battery is good at all. After the truck sits overnight I can see about 11.6v via FORScan (key on, engine off)

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[Graygoose2021]

try the BMS reset first, may clear all your issues.
And restart you stop/start

 

[jborbs]

try the BMS reset first, may clear all your issues.
And restart you stop/start

How do you recommend I do that? There are so many random threads I've seen with people doing dances ranging from "do nothing overnight" to "stand on your head while flashing the high beams and disconnecting the negative battery cable with your nose"

 

[Graygoose2021]

I did the key on, brights 5x, and brakes 3x....worked, turned all my interior lights back on. It stopped for awhile, due to bad battery. Eventually, I just added a new battery. But yours reads good voltage

 

[jborbs]

I did the key on, brights 5x, and brakes 3x....worked, turned all my interior lights back on. It stopped for awhile, due to bad battery. Eventually, I just added a new battery. But yours reads good voltage

Thanks! I did find this elsewhere too but wasn't sure how trustworthy it was:

1. Switch ignition on, and leave the engine off.​

Note: Complete Steps 2 & 3 within 10 seconds.​

2. Flash the high beam headlamps five times, ending with the high beams off.​

3. Press and release the brake pedal 3 times.​

The battery warning lamp flashes 3 times to confirm that the reset is successful.​

​

I did that, the light flashed 3x. So I'll take another drive in a bit and see if things are back to normal - if they are, and it keeps happening, I'll consider a battery replacement. I know they're not good forever though I would expect a young AGM like this (barely over 2 years since the truck was manufactured) to be serviceable still.

Thanks so much!

 

[Tall Tail]

You could have your battery load tested at a local auto parts store.

 

[Graygoose2021]

Cool, let us know how it works out!

 

[jborbs]

Cool, let us know how it works out!

Well, I went and drove around for an hour or so - normal mode, highway and city both, and it still won't activate the auto start/stop. The icon comes up with the slash through it in the instrument panel so I know it's thinking about it, but is still inhibited.

 

[Bryan Simon]

My pickup was just over a year when this stated going on.
Checking voltage in the morning, battery as low as 11.6 on a few days.
Dealer charged it and claimed all is good.
Not really, worked for a few days.
Later in the year , a long trip to Las Vegas and things were working again—til a few days after getting home.
Then windows started freaking out and and truck would slip into a coma immediately after shutting it off. No dome lamps no welcome screen upon door opening.
Another trip to the dealer—-battery replaced and everything working fine so far, but it’s only been about 4 months.

an occasional daytrip out of the county may be needed to keep the battery up. My regular commute is about 20 mi one way and that was not getting it done, particularly since I the trucke is parked on accessory for about 90 min a day (like it is right now).

 

[riverdave]

Well, I went and drove around for an hour or so - normal mode, highway and city both, and it still won't activate the auto start/stop. The icon comes up with the slash through it in the instrument panel so I know it's thinking about it, but is still inhibited.

After leaving my truck for 9 days it went into "deep sleep mode" and the battery issues began. It started/ran fine but the auto start/stop was gone. Morning readings below 12V, OK after daily drive, then low again every morning. I had a new battery installed under warranty, all good now. There are a few very informative threads here on this topic. I now use a battery tender if truck is parked for extended periods.

 

[jborbs]

Thanks all, I’ve seen some of those threads too. I have a good quality tender in the garage and will try topping it up overnight and see if things are normal (for any period of time, however brief) afterwards.

 

[jborbs]

Well, I don't know what combination of things made it happen, but we did it, people. It's been raining so much I didn't hook up the battery tender overnight, but everything is back to normal again. I guess I just need to keep an eye on how much I drive it.

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