Jumperless Aux Battery Bypass

[miketomp1972]

Here's my JL negative cables. Changed again! The aux battery is the flat with post that's attached with small bolt. I will need to swap to a longer bolt to add my winch and compressor ground to.
There on to us and making it harder that just removing a wire. Damn them!

My JT was just opposite.

I’m dying over here, 2020 3.6L main battery tests 12.7 - I disconnect both grounds each and a dead Jeep, hook them both back up and Jeep starts.. I’m baffled..
yanked F42
Disconnected smaller ground
Then larger one
Will not start without both grounds connected. Ugh

Sponsored

 

[mdkautzman]

I’m dying over here, 2020 3.6L main battery tests 12.7 - I disconnect both grounds each and a dead Jeep, hook them both back up and Jeep starts.. I’m baffled..
yanked F42
Disconnected smaller ground
Then larger one
Will not start without both grounds connected. Ugh

You only unhook the smaller gauge ground. Leave the larger one hooked up.

 

[mdkautzman]

Question is are we really sure we're bypassing the aux battery. N3 is still hot???? Is there maybe another ground somewhere.

 

[miketomp1972]

You only unhook the smaller gauge ground. Leave the larger one hooked up

You only unhook the smaller gauge ground. Leave the larger one hooked up.

sorry I should of explained it better no matter which one I disconnected the jeep will not start unless both are connected. Smaller ground off only and nothing, larger ground off and nothing then I connect both back on and it starts. Main battery 12.7 disconnected and out of the jeep.

 

[Stuckinthesand]

Question is are we really sure we're bypassing the aux battery. N3 is still hot????

As long as the ground is disconnected and fuse pulled it bypasses the aux. The PCR is what makes the batteries work together by having them connected in parallel. By pulling the fuse and removing the negative terminal you are taking the aux out of the equation. Just like the main battery without a negative you don’t have power to anything. Now if you didn’t pull the fuse and only disconnected the negative terminal you would get the error symbol on your EVIC. By pulling the fuse you are stopping the system from doing a self test on the aux battery. This is why it is still necessary to deactivate start/stop even with the aux disconnected. You can never truly delete the aux setup. It would just use the main battery in a start/stop situation if not deactivated.

 

[Stuckinthesand]

sorry I should of explained it better no matter which one I disconnected the jeep will not start unless both are connected. Smaller ground off only and nothing, larger ground off and nothing then I connect both back on and it starts. Main battery 12.7 disconnected and out of the jeep.

I would put the main on a charger overnight and check again. I just had my main die on me last week even though it was showing 12.7 on the EVIC soon as I tried to start it it just clicked. If I jumped it I had to keep it in neutral and the rpm’s at 1500 or so to keep it from stalling out. Replaced the main and everything is normal again. Your aux could be giving juice to the main and vice versa.

 

[miketomp1972]

As long as the ground is disconnected and fuse pulled it bypasses the aux. The PCR is what makes the batteries work together by having them connected in parallel. By pulling the fuse and removing the negative terminal you are taking the aux out of the equation. Just like the main battery without a negative you don’t have power to anything. Now if you didn’t pull the fuse and only disconnected the negative terminal you would get the error symbol on your EVIC. By pulling the fuse you are stopping the system from doing a self test on the aux battery. This is why it is still necessary to deactivate start/stop even with the aux disconnected. You can never truly delete the aux setup. It would just use the main battery in a start/stop situation if not deactivated.

yes I did have f42 pulled the ESS and disconnected the thinner ground, jeep did nothing then I switched the grounds and nothing and then hook them both back up and the jeep starts. Took the battery out it reads 12.7 while it was out I confirmed smaller ground was the aux and did it again, fuse is out, removed small ground and nothing.. hook them both back up and she starts again.

 

[mdkautzman]

As long as the ground is disconnected and fuse pulled it bypasses the aux. The PCR is what makes the batteries work together by having them connected in parallel. By pulling the fuse and removing the negative terminal you are taking the aux out of the equation. Just like the main battery without a negative you don’t have power to anything. Now if you didn’t pull the fuse and only disconnected the negative terminal you would get the error symbol on your EVIC. By pulling the fuse you are stopping the system from doing a self test on the aux battery. This is why it is still necessary to deactivate start/stop even with the aux disconnected. You can never truly delete the aux setup. It would just use the main battery in a start/stop situation if not deactivated.

Cool. I have the tazer so no pushing button and I did pull fuse.
Any ideas what's going on with miketomp1972?

 

[WranglerDad]

Thanks for those who helped me on a separate thread. I’m bypassing by removing the hood pin for ESS and will pull the fuse. I have removed the Aux battery. I just don’t know what to do with the red positive lead? Attach it to the main? Sorry for being obtuse.

 

[Stuckinthesand]

yes I did have f42 pulled the ESS and disconnected the thinner ground, jeep did nothing then I switched the grounds and nothing and then hook them both back up and the jeep starts. Took the battery out it reads 12.7 while it was out I confirmed smaller ground was the aux and did it again, fuse is out, removed small ground and nothing.. hook them both back up and she starts again.

I think we posted at the same time. Look at post #66 for my recommendation. That is the only thing I can think of at this point. Even if it shows 12.7 that isn’t with a load on it. With a load on it it may be below 12.7 and you are getting a boost from the aux.

 

[Stuckinthesand]

Thanks for those who helped me on a separate thread. I’m bypassing by removing the hood pin for ESS and will pull the fuse. I have removed the Aux battery. I just don’t know what to do with the red positive lead? Attach it to the main? Sorry for being obtuse.

Yes you need to route it back up to the main. If you pull the fuse no need to remove the hood pin.

 

[miketomp1972]

Cool. I have the tazer so no pushing button and I did pull fuse.
Any ideas what's going on with miketomp1972?

Taser mini is installed and operates awesome I’m baffled…. After both grounds were secured I started the jeep and drove it without the fuse in and no dash light either, Im totally at a loss for words I followed everyones directions as if it weren’t easy enough but testing my battery out of the jeep was just an added bonus to help figure out what is going on.

 

[WranglerDad]

Yes you need to route it back up to the main. If you pull the fuse no need to remove the hood pin.

Awesome. Thanks so much for clarifying. I got a new wire to extend and attach it - unless there’s a trick to getting the OEM one to connect!? Mine seems just short of reaching …

 

[Stuckinthesand]

Awesome. Thanks so much for clarifying. I got a new wire to extend and attach it - unless there’s a trick to getting the OEM one to connect!? Mine seems just short of reaching …

I haven’t done it I just left my aux in but disconnected. From what I have seen from
others though is that it can be re-routed to reach the main but it is a pain.

 

[Jebiruph]

Awesome. Thanks so much for clarifying. I got a new wire to extend and attach it - unless there’s a trick to getting the OEM one to connect!? Mine seems just short of reaching …

I would leave your aux cables in place in case you ever want to revert back. Just make sure the positive cable can't short out on anything. The only reason to connect the aux positive to the main positive is if you still want ESS to work.

I would advise against making changes you don't fully understand, if you have related issues who is going do the troubleshooting? There's lots of information here https://www.jlwranglerforums.com/forum/threads/3-6l-ess-dual-battery-consolidated-information.25377/ .

Leaving the aux battery in place and pulling fuse f42 and the aux negative leaves the factory setup mostly in place but stills removes the aux from the system.

Sponsored