Jumperless aux battery/PCR bypass

[Gvsukids]

I was reading last night that it might take up to five extended power cycles for the battery sensor to reset itself. Not sure if that would trigger the light or not.
The thread on the Wrangler forums seems to be covering the issues better.

FACT - it only takes a couple of starts with about 3 hours sitting in between. It usually learns in a single morning or afternoon.

The @! light went off on the drive home.

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[ShadowsPapa]

W

The @! light went off on the drive home.

Would be interesting to have seen the codes behind the light.

 

[Lunentucker]

The @! light went off on the drive home.

Good deal. I'm guessing erroneous voltage info from the sensor was triggering it. But what do I know?

 

[jebiruph]

The @! light went off on the drive home.

If you started the engine with the aux disconnected and the fuse installed, the @! gets triggered and can take awhile to clear on it's own.

 

[ShadowsPapa]

If you started the engine with the aux disconnected and the fuse installed, the @! gets triggered and can take awhile to clear on it's own.

BINGO!
It takes a few starts to realize the error no longer exists and it will clear. In that way it's no different than any other MIL - say, for a misfire. Once you have 2 or 3 starts and runs with no misfire, the light may clear (mine did)

The system saw an issue - subsequent starts without that issue cleared the light.

Good deal. I'm guessing erroneous voltage info from the sensor was triggering it. But what do I know?

LOL - actually, you know a lot - I've seen enough of your stuff......
But in this case, sorry, honestly, no, the IBS wasn't involved.. It would have reported current voltage of the crank battery when it was first fired up. And the ESS couldn't care less about that.


I was swapping parts in the tanks in my shop and while doing that mindless work - it hit me, what if it was similar to the MIL (check engine light) and the error was no longer there.
But I spilled passivate on my hand (which is now stained a really beautiful orange) and Jerry, the smart one of the bunch, had the idea.

 

[Gvsukids]

W

Would be interesting to have seen the codes behind the light.

I should clarify that the light wasn't on when I left from work.

 

[ShadowsPapa]

I should clarify that the light wasn't on when I left from work.

Then it ran its check and found no problem and cancelled the all hands on deck annoying light.
In any case, my money is on what Jerry said.

 

[Maximus Gladius]

If you get 12+ volts, that is the aux battery ground cable.
If you get only a couple of volts, and perhaps some sparks, then it is the main battery ground cable to the chassis and block.
Remove the lower cable that's connected directly to the IBS via the shorter stud,
Connect volt meter to that and the main battery + terminal.
12 volts should be seen, indicating THAT is the ground cable from the aux battery.

Tying to remove the aux (-) from the main crank battery, I took off the larger cable from the large stud and put the multimeter on it and the crank (+) and the numbers were all over the place, not even a V or 2 at most, but very jumpy. That told me that (-) wasn’t from the aux. You mention if that’s the case, take off the other (-) cable on top of the IBS but you can’t. The only way to remove the aux (-) is right at the aux battery. …unless I’m missing something, the cable at the IBS is not a post and nut but a whole plate that can’t be removed.

 

[ShadowsPapa]

Tying to remove the aux (-) from the main crank battery, I took off the larger cable from the large stud and put the multimeter on it and the crank (+) and the numbers were all over the place, not even a V or 2 at most, but very jumpy. That told me that (-) wasn’t from the aux. You mention if that’s the case, take off the other (-) cable on top of the IBS but you can’t. The only way to remove the aux (-) is right at the aux battery. …unless I’m missing something, the cable at the IBS is not a post and nut but a whole plate that can’t be removed.

In this picture, likely the opposite of a 2020, there's a 1 and a 2 nut.
Imagine that the top nut is off and my winch and plow cable are removed.
That leaves you with nut #2 - that removes that cable from the plate that is part of the end of cable #1

Remove nut #1 and then the cable comes off the top of the IBS.
Once that is removed you should see the copper that is the top of the IBS.

This is my 2020 - I removed the one cable from the taller stud and on my 2020, THAT was the ground for the aux battery.

The other is still on the top of the IBS - but can be removed.

Once both cables are off - you should see this -

But do be aware at some point they switched the top and bottom ground cables. At one point the first to come off was aux ground, then on others, the bottom cable with the larger plate on the end was the aux ground.

 

[Maximus Gladius]

In this picture, likely the opposite of a 2020, there's a 1 and a 2 nut.
Imagine that the top nut is off and my winch and plow cable are removed.
That leaves you with nut #2 - that removes that cable from the plate that is part of the end of cable #1

Remove nut #1 and then the cable comes off the top of the IBS.
Once that is removed you should see the copper that is the top of the IBS.

This is my 2020 - I removed the one cable from the taller stud and on my 2020, THAT was the ground for the aux battery.

The other is still on the top of the IBS - but can be removed.

Once both cables are off - you should see this -

But do be aware at some point they switched the top and bottom ground cables. At one point the first to come off was aux ground, then on others, the bottom cable with the larger plate on the end was the aux ground.

My 2021 crank (-) cable is the larger one on the 13mm post. If I remove the other one on top of the IBM (that is the plate that has the larger post connected) I then have to reconnect the 13mm crank cable on to the top of the IBM that’s a 10mm. ??

Use washers, yes? That’s probably the ‘work-a-round’ solution.

 

[Maximus Gladius]

I’ve read lots of explanations on ‘how to’ do this but no photos showing the 13mm on top of the 10mm post (IBM).

 

[Mr._Bill]

Tying to remove the aux (-) from the main crank battery, I took off the larger cable from the large stud and put the multimeter on it and the crank (+) and the numbers were all over the place, not even a V or 2 at most, but very jumpy. That told me that (-) wasn’t from the aux. You mention if that’s the case, take off the other (-) cable on top of the IBS but you can’t. The only way to remove the aux (-) is right at the aux battery. …unless I’m missing something, the cable at the IBS is not a post and nut but a whole plate that can’t be removed.

If you are trying to isolate the two batteries to charge or check voltage, just disconnect the positive assembly from the main battery post and leave everything else connected. The reading from the battery post and negative gives you the main battery. The reading from the disconnected positive assembly and negative gives you the aux battery. Just be careful not to touch the positive assembly against anything else, as that can blow the main fuse at the N connectors.

 

[Maximus Gladius]

If you are trying to isolate the two batteries to charge or check voltage, just disconnect the positive assembly from the main battery post and leave everything else connected. The reading from the battery post and negative gives you the main battery. The reading from the disconnected positive assembly and negative gives you the aux battery. Just be careful not to touch the positive assembly against anything else, as that can blow the main fuse at the N connectors.

You are correct here. What others are suggesting for a simple and cheap aux delete is to remove the f42 fuse AND the aux negative cable from the main crank battery.

In order to do this for my 2021 JTR, the aux (-) is a 10mm and is the plate on top of the IBM and is also the holder of the 13mm post for the main crank (-) cable.

So for those wanting to delete the aux, they are not just isolating or checking the aux. Working up top on what’s accessible, one will be faced with having to connect the 13mm crank battery (-) back onto a 10mm IBM post. ….or just go after the aux battery and physically remove it and leave the cables there with the ends taped off.

 

[Maximus Gladius]

Couldn’t you just disconnect the aux (+) up top and tape that off and be just fine to leave the ground alone?? If the aux is proving to be that parasitic draw on the main, would undoing the (+) aux but leaving the (-) attached be the same as removing the aux (-)?

 

[Mr._Bill]

Couldn’t you just disconnect the aux (+) up top and tape that off and be just fine to leave the ground alone?? If the aux is proving to be that parasitic draw on the main, would undoing the (+) aux but leaving the (-) attached be the same as removing the aux (-)?

If you disconnect and remove the Aux Battery Positive cable, it doesn't really matter what you do with the negative cable. If you just tape the positive cable and leave it hanging, there is always the possibility of it shorting against something and blowing the big fuse at the N connectors.

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