AUX Delete getting cancelled by accessory ground

[Tyler-98-W68]

Technically, the AUX (ESS) battery ground wire/path goes "over" the IBS, not through it. The IBS monitors only CR[an]]K battery current.

The IBS monitors ALL power going in and out of the main AUX battery, and except when the AUX battery is disconnected during a ESS event. It doesn't just monitor cranking current.

I've been monitoring the IBS on different jeeps for years and it does far more than measure cranking current.

Example

This is me running a 2000w inverter off the H7 battery in my 4Xe without it running,

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[THAW]

The IBS monitors ALL power going in and out of the main AUX battery, and except when the AUX battery is disconnected during a ESS event. It doesn't just monitor cranking current.

I've been monitoring the IBS on different jeeps for years and it does far more than measure cranking current.

Example

This is me running a 2000w inverter off the H7 battery in my 4Xe without it running,

The current paths work thusly:

(from: 3.6L ESS IBS Information)

So, the IBS monitors all CR[an]K/main battery current, and does not monitor any AUX (ESS) battery current.

 

[Tyler-98-W68]

I'm well aware of how it works....you had said it only monitors cranking current......which was incorrect.

I have a lithium battery hooked up to my AUX battery with a shunt, so I can watch the current during ESS events, there isn't a whole lot of draw on the AUX battery during a ESS event.

 

[THAW]

I'm well aware of how it works....you had said it only monitors cranking current......which was incorrect.

I wrote "CR[an]K battery current" (not current during cranking). The "main" battery is commonly referred to as a "crank" battery, and is labeled "CRK BATT" on the PDC lid fuse map.

 

[Tyler-98-W68]

Ok cool....so do you just look at wiring diagrams or actually test out how the system draws power ect?

 

[THAW]

Ok cool....so do you just look at wiring diagrams or actually test out how the system draws power ect?

I'm not sure what you're asking with regard to power draw tests.

I do pull up JScan IBS stats on my phone every few drives, especially before and after external charging; I've watched current and voltage extensively on long trips. And, I've done lots of accessory wiring projects on my Jeep.

 

[Tr4ckD4ys]

Ok but that means I had the negative cable to body ground removed and isolated. Shouldn’t that mean the power is completely gone then, with negative clamp from post of negative main battery fully removed? I guess in that case my AUX negative was still attached to the bundle but still - I don’t understand why there was power still. Is it at all possible that there is sufficient residual power in the system after disconnecting that it could still move the seat for a little while before dying?

 

[THAW]

Ok but that means I had the negative cable to body ground removed and isolated. Shouldn’t that mean the power is completely gone then, with negative clamp from post of negative main battery fully removed? I guess in that case my AUX negative was still attached to the bundle but still - I don’t understand why there was power still. Is it at all possible that there is sufficient residual power in the system after disconnecting that it could still move the seat for a little while before dying?

It doesn't seem to add up.

Can you reproduce it?

 

[Tr4ckD4ys]

It doesn't seem to add up.

Can you reproduce it?

I shall!

 

[jadmt]

Ok but that means I had the negative cable to body ground removed and isolated. Shouldn’t that mean the power is completely gone then, with negative clamp from post of negative main battery fully removed? I guess in that case my AUX negative was still attached to the bundle but still - I don’t understand why there was power still. Is it at all possible that there is sufficient residual power in the system after disconnecting that it could still move the seat for a little while before dying?

I had the same thing I disconnected the negative completely from the battery and I still had full power...I totally isolated both negatives after pulling the main clamp off the battery and still having full power I removed the smaller cable from the battery clamp and still had power..I was so confused I thought it was just residual power so I decided to try and start my jeep and it started...I figured I was in over my head so I just hooked the negative cables back up......and called it a day..2024 jeep.

 

[Tr4ckD4ys]

I had the same thing I disconnected the negative completely from the battery and I still had full power...I totally isolated both negatives after pulling the main clamp off the battery and still having full power I removed the smaller cable from the battery clamp and still had power..I was so confused I thought it was just residual power so I decided to try and start my jeep and it started...I figured I was in over my head so I just hooked the negative cables back up......and called it a day..2024 jeep.

See! I knew it! It’s something with the MY24+ Jeeps. Stellantis changed plenty in the engine bay. I’ve tried working on the turbo, intake and exhausts and everything is “slightly” different.

I am starting to get the impression they’ve built in a fail safe to prevent people from doing the F42-aux-delete

 

[Tr4ckD4ys]

It doesn't seem to add up.

Can you reproduce it?

I had the same thing I disconnected the negative completely from the battery and I still had full power...I totally isolated both negatives after pulling the main clamp off the battery and still having full power I removed the smaller cable from the battery clamp and still had power..I was so confused I thought it was just residual power so I decided to try and start my jeep and it started...I figured I was in over my head so I just hooked the negative cables back up......and called it a day..2024 jeep.

OK - I’ve done the experimentation. Below is my findings (and follow-up questions). I have also captured everything on video but I believe it’s unnecessary to bother you with my German accent considering the mystery is solved below.

With everything returned to factory/stock (F42 Fuse inserted, AUX Battery present, All cables and terminals connected):
- Test 1 “Proof that power is gone when disconnecting the thicker cable held by the 13mm nut”: As the title of this test said, when I disconnect the cables held by the 13mm nut (thick vehicle cable and 4AWG ground cable from my WARN Winch), the power to the vehicle is fully cut, whether or not I remove the clamp from the negative terminal.The cable held by 13mm nut is the thicker one. The cable held by the IBS nut is the thinner one.
- Test 2: “Proving power is on even with F42 pulled and thicker cable held by 13mm nut isolated”: As the name suggests, I was able to prove that in the case of F42 removed and the thicker cable isolated, the power to the Jeep is present.
- Test 3: “Reconnecting my 4AWG WARN Winch ground cable”: When reconnecting this cable to the negative battery post, held by the same 13mm nut, power to the jeep fully returned, despite F42 being gone and the thicker vehicle cable isolated.

So there we have it. The solution to my mystery is that when I connect my WARN winch ground cable to the main battery negative post, I have power running through the vehicle, even in the case of F42/thick cable isolation. My only question now is: Why?

Of course it appears the safest solution now is to fully remove the AUX battery. I suspect that this will also solve the case above where my winch ground is causing power to flow.

 

[Jebiruph]

Your winch is grounded to the body and when you connect the negative winch cable to the battery, the battery is grounded to the body through the winch.

Nothing you do with the aux battery or F42 will have any affect on this.

 

[RubiSc0tt]

Sorry I'm late. You need to pull the cables that go from the main battery to the Aux battery and jumper one of the posts. See here:


you can follow all the fun I had in my thread:
https://www.jlwranglerforums.com/fo...mly-tries-to-shut-down-another-thread.157903/

Long story extremely short:
Aux battery was dying and causing all sorts of electrical hijinx. I pulled Fuse 42 and Negative terminal and it persisted/ got worse. When I finally removed the Aux battery it stopped but the negative terminal on the Aux sparked. Why? It was still connected to the system. So I taped it off and drove it for a bit. Noticed a voltage drop while driving so instead of drawing "extra" on my brand new big battery, I just bit the bullet and bought a new aux battery. No more issues.

 

[THAW]

So there we have it. The solution to my mystery is that when I connect my WARN winch ground cable to the main battery negative post, I have power running through the vehicle, even in the case of F42/thick cable isolation.

That explains it!

Of course it appears the safest solution now is to fully remove the AUX battery. I suspect that this will also solve the case above where my winch ground is causing power to flow.

Disconnect the "thinner" cable and remove fuse F42, and your AUX (ESS) battery will be disconnected the way you want.

The winch ground wire won't keep the AUX (ESS) battery connected f you remove the proper ("thinner") cable terminal connector. What happened is you disconnected the body ground ("thicker" cable) instead of disconnecting the AUX (ESS) battery ground, so your AUX (ESS) battery ground ("thinner") cable was still grounded through the winch/cable. You want to break the connection between the AUX (ESS) battery and the 2 body ground cables (factory and winch) by disconnecting the "thinner" cable.

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