Isolating AUX battery. Which negative cable?

[Mr._Bill]

All, you won't want to hear this .. I did exactly this and guess what still operates - intermittently ? Start STOP functioned 2 times yesterday; checked with my other driver and he reported same only occasionally and without any unusual operations. Put fuse 42 back in left cable disconnected and reverted to using the BUTTON to Turn Off. Any and All thoughts appreciated.

Removing the Fuse and disconnecting the Aux battery does not prevent ESS from activating. It just shifts all the electrical load to the Main battery. The Aux battery is there to keep the computers and electronics stable. The ESS system is always active and cannot be removed or disabled. The button on the dash, and the various hacks and devices available, only prevent the ESS from turning off the engine when it would normally do so.

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[ducatijosh]

What's the purpose of removing Fuse 42 then?

 

[High Alextude]

What's the purpose of removing Fuse 42 then?

The purpose of removing fuse 42 is to turn off the ESS warning light, not to turn ESS completely off. When you remove just the cable, a warning light will come on, hence fuse 42.

 

[ShadowsPapa]

The purpose of removing fuse 42 is to turn off the ESS warning light, not to turn ESS completely off. When you remove just the cable, a warning light will come on, hence fuse 42.

F42 isn't for the warning light.
F42 is the fuse for the PCR relay. It's the feed for the PCR circuit.

With the relay disabled, when the PCM tries to cause the PCR to open so it can check the aux battery condition, the relay can't operate but the PCM doesn't know this.
So what pulling that fuse does is to prevent the PCM from opening the PCR to check the battery.
If you leave the fuse in, the PCM will trigger the PCR to open so it can check the aux battery. If the battery isn't there, you get an error condition.
If you pull that fuse, it can't open the relay so what the PCM sees is the MAIN battery voltage, it doesn't then know the aux battery is missing. So ESS will operate normally - some have said up to 6 times before it stops working, I've not proved that as I have zero intention or desire to disconnect the aux battery or pull that fuse. Not worth my time.

 

[Rufingit]

The one marked 2020 is the aux battery ground cable for model year 2020

The one marked 2021+ is the aux battery ground cable for model year 2021 and later

The arrow points to the IBS - DO NOT REMOVE THAT! It's NOT part of the auto/stop start system.
Again, DO NOT REMOVE the IBS, it has nothing to do with anything ESS related, nothing.

The one marked 2020 is the aux battery ground cable for model year 2020

The one marked 2021+ is the aux battery ground cable for model year 2021 and later

The arrow points to the IBS - DO NOT REMOVE THAT! It's NOT part of the auto/stop start system.
Again, DO NOT REMOVE the IBS, it has nothing to do with anything ESS related, nothing.

I have a 2021 Gladiator and tried to do the aux batt delete as previously described. As shown in your picture, the main and aux batt neg cables are attached, via a metal bridge, to a post on the IBS. The post on the IBS is much smaller than the post the main batt neg cable is attached to. As a result, it doesn’t appear that a solid ground of the main neg batt cable to the IBS is achievable. Am I overthinking this or do you have any suggestions?

 

[Lunentucker]

I have a 2021 Gladiator and tried to do the aux batt delete as previously described. As shown in your picture, the main and aux batt neg cables are attached, via a metal bridge, to a post on the IBS. The post on the IBS is much smaller than the post the main batt neg cable is attached to. As a result, it doesn’t appear that a solid ground of the main neg batt cable to the IBS is achievable. Am I overthinking this or do you have any suggestions?

Overthinking.

 

[ShadowsPapa]

Overthinking.

yeah, After all, it's holding both ground cables to the IBS before any mods, so it's going to hold just one.
The only "negative" is that in the 21 and later you lose that large stud to connect things to, but then you always have chassis grounds or connectors like Tysongladiator shows in his youtube video.

I have a 2021 Gladiator and tried to do the aux batt delete as previously described. As shown in your picture, the main and aux batt neg cables are attached, via a metal bridge, to a post on the IBS. The post on the IBS is much smaller than the post the main batt neg cable is attached to. As a result, it doesn’t appear that a solid ground of the main neg batt cable to the IBS is achievable. Am I overthinking this or do you have any suggestions?

it's not a big deal in any case. Put the chassis ground back on the top of the iBS and use the supplied nut.
the contact is between the top of the IBS and the cable terminal, not the nut itself.

 

[ShadowsPapa]

Here's where the connection is important - the flat of the cable terminal against the copper of the IBS, the stud and nut are mostly to clamp the two together although of course some is conducted through the nut's lower face against the top of the cable terminal............

 

[ecidiego]

It's been over 2 years so I pulled and seperated the aux, chassis, and ibs off the main neg post. Aux and Main both measured 12.4vdc when isolated. Hooked up the 10a Noco to the main pos clamp and aux neg.... charging at only 700mA.

Unicorns? I only drive the truck 2 or 3x a week on short trips unless heading out for wheelin.

 

[ShadowsPapa]

It's been over 2 years so I pulled and seperated the aux, chassis, and ibs off the main neg post. Aux and Main both measured 12.4vdc when isolated. Hooked up the 10a Noco to the main pos clamp and aux neg.... charging at only 700mA.

Unicorns? I only drive the truck 2 or 3x a week on short trips unless heading out for wheelin.

0.7 amps and the battery started out at only 12.4 volts? Seems low to me.
But what's the voltage it's charging at?

 

[ecidiego]

0.7 amps and the battery started out at only 12.4 volts? Seems low to me.
But what's the voltage it's charging at?

14 7.

Noco Genius 10 charger.

 

[ecidiego]

down to 300mA now....charger solid green.... charger thinks it's fine I guess?

edit...back to 700mA and slow flashing....i think it's at the ene of whatever 'program' it's running.

 

[ecidiego]

0.7 amps and the battery started out at only 12.4 volts? Seems low to me.
But what's the voltage it's charging at?

Charger switched to maintenance, removed it and Aux measures 12.7v isolated after 90 minutes.

Switched negative charger to main neg post.... it immediately went to 7.5A then backed down to 500mA.

My batteries just seem 'fine' I guess. I do have the 240A alt....I wonder if it's able to maintain these better?

IBS, aux neg, and chassis ground all removed, isolated, and not touching anything.

 

[20Silver20]

The one marked 2020 is the aux battery ground cable for model year 2020

The one marked 2021+ is the aux battery ground cable for model year 2021 and later

The arrow points to the IBS - DO NOT REMOVE THAT! It's NOT part of the auto/stop start system.
Again, DO NOT REMOVE the IBS, it has nothing to do with anything ESS related, nothing.

Thanks for the great info.

 

[Rwalk31]

I’m trying to isolate my AUX battery and pull fuse 42 until I can decide what I want to do with my battery setup.

Can anyone help me confirm which cable it is from the negative post? I heard 2 different answers from my research. Mine is a 2020.

Please excuse the dust from all the wheeling trips.

I know this is an old thread and you figured it out but for anyone who ends up here, the aux cable has a yellow and black tag on it that clearly states it is the aux battery cable. Just did this myself

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