Auxiliary battery?

[Kanuck]

Go to your screen settings in front of you, toggle to MPG data, then scroll to ASS. It will tell you why it's not working.

I bet $ on your main battery.

That maybe on the higher trims or 22's and later. My 21 XLT doesn't have that.

Sponsored

 

[SaSurvival]

I’m being told by a service manager that because I have an auto stop start feature on my 21 3.5L ecoboost that I have a second auxiliary battery. My auto stop start has never worked, so if I have one I think it is dead. I have watched videos and it says it was behind the passenger side rear seat. All that is there is an inverter…. Do I have a second auxiliary battery??? If so where is it??

We have an Aux batt but it is for the 2KW pro power on board and it is under the passenger rear seat. But this has nothing to do with the main batt.
I have had the same issue with my 2018 and my 2022, I learnt quick that the SOC is low and the ASS does not work and sleep mode was activated regularly.
My dealer on my 22 saw I had unplugged Garmin Inreach, USB key (music, back up trailer camera) on the dash and blamed that, and wouldn’t do anymore, I gave up with them and added a 2amp trickle charger as our truck currently does short trips, I plug it in nightly and ASS works perfectly, sleep mode does not come on anymore. This is my simply solution.
I am a tech for another brand and explained my findings to them and they didn’t care.

 

[woodardl08]

That maybe on the higher trims or 22's and later. My 21 XLT doesn't have that.

 

[Kanuck]

Is tha

Is this when you try and turn the ASS on? Mine is disabled, so I never see this message.

 

[woodardl08]

When I went in for the fuel, economy and pressed auto start stop, that’s what it said.

 

[AndreB]

I believe that aux battery is on power boost models. Never had one on my eco boost

I have a 2023 Latiat with 2kw pro power (not the 2.4kw). This battery is used for the 120v AC inverter if not mistaken.

 

[KTM753]

I have a 2023 Latiat with 2kw pro power (not the 2.4kw). This battery is used for the 120v AC inverter if not mistaken.

It's actually (2) 12 volt in series. The 2nd alternator under your hood is a 24 volt alternator. I have the same 2.0 kW Pro-Power on my F-150.

 

[KTM753]

Did you buy your truck new or used?

One Forscan method of disabling Auto Start Stop is coding a steering movement as always on. This disables ASS. Maybe a previous owner turned this on in Forscan and now your ASS won't work no matter your battery voltage.

This is where I would go next if I were you. Do you have a Forscan compatible cable/dongle? Ever used the software? If not, we can help get you going in Forscan, it's worth it to disable all the warning chimes also...

 

[AndreB]

It's actually (2) 12 volt in series. The 2nd alternator under your hood is a 24 volt alternator. I have the same 2.0 kW Pro-Power on my F-150.

Thanks for the precision.

2 more batteries to monitor in a few years. ?

 

[Gros Ventre]

When a starter motor kicks in the current draw causes system voltage to dip. The "Auxiliary" battery under the back seat is a "keep alive" battery to ensure the voltage dip does not cause a glitch in the truck's memory circuits caused by that dip. This battery is "auctioneered" (EG whatever voltage is highest supplies the circuits) for key circuits by the circuitry thus ensuring continued engine operation.

Sponsored