Aux battery, delete, now working again. ???

[Planerdude]

2021 Mojave, 38 months old with 35,0000 miles.
Auto start/stop quit working at 24 months, dealer replaced aux battery under warranty. Took 1 week for auto start stop to start working again.
3 months ago auto start stop quit working again.
Pulled the 42 fuse and the negative lead from the aux battery at the main battery terminal. Left the aux battery in place. (Delete complete).
2 days ago, Main battery goes out. Normal for Las Vegas, 3 years is typical life span.
Replaced main battery with the larger group 94r
Size. Did NOT reverse the aux delete.
All fine now Including the auto. Start/stop working normally! Why ????????

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[CrazyCooter]

Your main battery was defective at the time the dealer diagnosed and now you have a strong battery that maintains voltage?

 

[Lunentucker]

It's working off of the new main battery. The bypass and fuse pull doesn't disable it.

Certain criteria must be met, and it's probably been too hot ambient until recently for it to meet all parameters.

 

[Mr._Bill]

2021 Mojave, 38 months old with 35,0000 miles.
Auto start/stop quit working at 24 months, dealer replaced aux battery under warranty. Took 1 week for auto start stop to start working again.
3 months ago auto start stop quit working again.
Pulled the 42 fuse and the negative lead from the aux battery at the main battery terminal. Left the aux battery in place. (Delete complete).
2 days ago, Main battery goes out. Normal for Las Vegas, 3 years is typical life span.
Replaced main battery with the larger group 94r
Size. Did NOT reverse the aux delete.
All fine now Including the auto. Start/stop working normally! Why ????????

Pulling the fuse just prevents the Aux battery startup test from working properly. The system gets a reading from the Main battery and thinks everything is okay. Pulling the fuse keeps the orange ESS error light from turning on, it does not disable ESS.

The batteries are paralleled together all the time, except during the startup test and during ESS events. One or both batteries starting to fail can pull the voltage low enough to prevent ESS from turning the engine off.

 

[Planerdude]

Pulling the fuse just prevents the Aux battery startup test from working properly. The system gets a reading from the Main battery and thinks everything is okay. Pulling the fuse keeps the orange ESS error light from turning on, it does not disable ESS.

The batteries are paralleled together all the time, except during the startup test and during ESS events. One or both batteries starting to fail can pull the voltage low enough to prevent ESS from turning the engine off.

 

[chorky]

It's important to note too that with the aux battery still installed, it could also be bad - meaning it might draw down your brand new battery and you could have a no-start situation. Emphasis on maybe and could. It's worth looking into.

Like others have said, pulling fuse 42 does NOT 'delete' the aux battery. The battery has to be physically disconnected or it is still in play.

 

[Planerdude]

Should I reconnect the neg cable and put the fuse back? Or keep things the way they are?

 

[Planerdude]

It's important to note too that with the aux battery still installed, it could also be bad - meaning it might draw down your brand new battery and you could have a no-start situation. Emphasis on maybe and could. It's worth looking into.

Like others have said, pulling fuse 42 does NOT 'delete' the aux battery. The battery has to be physically disconnected or it is still in play.

The neg cable is disconnected .

 

[chorky]

Should I reconnect the neg cable and put the fuse back? Or keep things the way they are?

That depends - do you want to have the aux battery or not?

 

[chorky]

it is possible for the ESS to function without the aux battery

 

[Mr._Bill]

Should I reconnect the neg cable and put the fuse back? Or keep things the way they are?

If you always hit the dash button to turn off ESS, it doesn't really matter. If you let ESS function, it will cause issues when the Main battery starts to degrade from age.

 

[Planerdude]

It's working off of the new main battery. The bypass and fuse pull doesn't disable it.

Certain criteria must be met, and it's probably been too hot ambient until recently for it to meet all parameters.

Then what exactly does the so called bypass do?

 

[Planerdude]

That depends - do you want to have the aux battery or not?

No

 

[Lunentucker]

Then what exactly does the so called bypass do?

It takes the AUX battery offline and makes the system function with just one battery, removing the chances of the AUX battery dying and taking the main battery with it. When not in ESS, the batteries are married as one, so if the AUX battery does begin to fail, it will continuously try to recharge from the man battery. A situation that can leave you stranded with little to no warning.

 

[Planerdude]

It takes the AUX battery offline and makes the system function with just one battery, removing the chances of the AUX battery dying and taking the main battery with it. When not in ESS, the batteries are married as one, so if the AUX battery does begin to fail, it will continuously try to recharge from the man battery. A situation that can leave you stranded with little to no warning.

So I should leave my delete in place? 42 fuse out and neg aux cable disconnected? Sounds good.

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