Jumperless Aux Battery Bypass

[azwjowner]

Everything's gonna be alright. Forum members are allowed to post what they want (non-political), including you. There's no thread-topic purity requirement.



Consider that the Aux Switch option alone supports 130 Amps (2 x 40A + 2 x 15A + 10A Ign + 10A B+) through N1. The Tow option 7-pin harness is another 30 Amps. That's 160 (optional) Amps without any Jeep electronics (climate, infotainment, USB/12V outlets, various control modules).

JL alternators are rated at 180/220/240 Amps, so sizing an N2 to N1 connection to that spec seems reasonable. The N3 post is fused at 150 Amps, so sizing an N3 to N1 connection for anything over 150 Amps is overkill.

It would be nice if Jeep would sell separately the shunt they put in the non-ESS Jeeps between N1 and N2, visible in the second photo of an Etorque electrical box here: https://www.jlwranglerforums.com/forum/threads/remote-start-issues-aux-bypass.124042/post-2589380

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[ScotM]

It would be nice if Jeep would sell separately the shunt they put in the non-ESS Jeeps between N1 and N2, visible in the second photo of an Etorque electrical box here: https://www.jlwranglerforums.com/forum/threads/remote-start-issues-aux-bypass.124042/post-2589380

I’m using the N1 to N3 with a 2 Awg or larger cable jumper from https://www.batterycablesusa.com/2-gauge-awg-extreme-battery-cable-with-ends
they will put 90 degree connectors on for no additional charge, just add it in the notes

 

[azwjowner]

I’m using the N1 to N3 with a 2 Awg or larger cable jumper from https://www.batterycablesusa.com/2-gauge-awg-extreme-battery-cable-with-ends
they will put 90 degree connectors on for no additional charge, just add it in the notes

I bought one of those years ago. I like to have all the options available so if my battery died and I suddenly decide to do the aux removal, I'm ready to go. Probably will go with my nickel-plated copper bus bar between N1 and N2 though.

 

[ScotM]

That works. Quite well, actually. It uses the 150A N3 fuse.

I'd bump the cable up to at least 2 gauge (last year, I got a 6-inch, 2-gauge cable with heat shrink-ed copper lugs for about $8 on Amazon).

So I was looking from the fender side today, and can see the n1/n3 connected to the PCM on the fire wall. So I can get to that easily. Separating the N1 and N3 out of the harness looks to be a challenge. Did you pull off all the high capacity fuse wires and pull them down into the area by the aux battery to separate the m out of the wiring harness, or will I need to remove the top of the fuse box and get at them that way. it looks like once the bottom of the aux battery housing and battery are removed there might be access that way.. Just trying to plan it out and look for things I can screw up before I dive into the actual removal.

That works. Quite well, actually. It uses the 150A N3 fuse.

I'd bump the cable up to at least 2 gauge (last year, I got a 6-inch, 2-gauge cable with heat shrink-ed copper lugs for about $8 on Amazon).

 

[THAW]

So I was looking from the fender side today, and can see the n1/n3 connected to the PCM on the fire wall. So I can get to that easily. Separating the N1 and N3 out of the harness looks to be a challenge. Did you pull off all the high capacity fuse wires and pull them down into the area by the aux battery to separate the m out of the wiring harness, or will I need to remove the top of the fuse box and get at them that way. it looks like once the bottom of the aux battery housing and battery are removed there might be access that way.. Just trying to plan it out and look for things I can screw up before I dive into the actual removal.

I believe you can pull the AUX (ESS) battery wiring down through the opened AUX (ESS) battery box, or up from the High Current Fuse side once the AUX (ESS) battery is disconnected. It might be a little tricky to get access to the wires from the High Current Fuse side, and to get the connectors through the pass-through opening. There's not a lot of access/room between the engine or the battery tray and the High Current Fuses to separate the harnesses, you'll definitely benefit from removing the CR[an]K/main battery.

[borrowed image]

 

[ScotM]

I believe you can pull the AUX (ESS) battery wiring down through the opened AUX (ESS) battery box, or up from the High Current Fuse side once the AUX (ESS) battery is disconnected. It might be a little tricky to get access to the wires from the High Current Fuse side, and to get the connectors through the pass-through opening. There's not a lot of access/room between the engine/battery tray and the High Current Fuses to separate the harnesses, you'll definitely benefit from removing the CR[an]K/main battery.

[borrowed image]

Excellent, I’ll remove the main, and then start from the bottom. If I can’t get it done, I can remove the top of the fuse box as a last resort

I believe you can pull the AUX (ESS) battery wiring down through the opened AUX (ESS) battery box, or up from the High Current Fuse side once the AUX (ESS) battery is disconnected. It might be a little tricky to get access to the wires from the High Current Fuse side, and to get the connectors through the pass-through opening. There's not a lot of access/room between the engine or the battery tray and the High Current Fuses to separate the harnesses, you'll definitely benefit from removing the CR[an]K/main battery.

[borrowed image]

so I undertook the extraction of the aux battery and wiring after lunch today. I got everything sorted, but in order to do so, I had to remove the fuse box. I just couldn’t see everything well enough with it in the way. Having done it once, I could probably do it again without removing the box. Hopefully, I didn’t f up the Jeep. I hope you (Thaw) can answer one question. there was a sensor plugged into the PCM on the fire wall. I think with fuse 42 removed it becomes just a wire. I plan on just taping it off. Any advice would be greatly appreciated.

 

[gm920]

Excellent, I’ll remove the main, and then start from the bottom. If I can’t get it done, I can remove the top of the fuse box as a last resort

so I undertook the extraction of the aux battery and wiring after lunch today. I got everything sorted, but in order to do so, I had to remove the fuse box. I just couldn’t see everything well enough with it in the way. Having done it once, I could probably do it again without removing the box. Hopefully, I didn’t f up the Jeep. I hope you (Thaw) can answer one question. there was a sensor plugged into the PCM on the fire wall. I think with fuse 42 removed it becomes just a wire. I plan on just taping it off. Any advice would be greatly appreciated.

Not a sensor, that is the PCM connector. Has no power with fuse 42 removed, just tape it up.

 

[ScotM]

Not a sensor, that is the PCM connector. Has no power with fuse 42 removed, just tape it up.

That’s what I was hoping. Thanks!!

 

[gm920]

That’s what I was hoping. Thanks!!

Your welcome, and it's PCR for Power Control Relay. People were removing that for the Aux bypass before someone discovered the fuse.

 

[ScotM]

Your welcome, and it's PCR for Power Control Relay. People were removing that for the Aux bypass before someone discovered the fuse.

Got it. PCR.. I did the simple aux bypass when my aux died, but then I didn’t want to leave the aux battery in there forever, and the thought of all the extra wire bouncing around just bugged me. So I’m just waiting on my jumper. I’m thinking I’ll do N3 to N1, since that is open now, instead of the N2 to N1. Everyone has been real helpful in educating Me. I do appreciate it., and it is an important distinction between a relay and a module for sure.

 

[jax501]

@AllMoparParts.com
Benny, could you please check if the "metal shunt" between N1 & N2 can be purchased? This shunt is found on etorque Jeeps next to the fuse box (e.g., V6 etorque, cuz no Aux battery)

See photo of shunt/connector between N1 & N2 circled (took photo from someone else's post).

 

[THAW]

Hopefully, I didn’t f up the Jeep. I hope you (Thaw) can answer one question. there was a sensor plugged into the PCM on the fire wall. I think with fuse 42 removed it becomes just a wire. I plan on just taping it off. Any advice would be greatly appreciated.

Already been answered sufficiently, but I'll add...

The PCR is a relay so it has a contact side and a coil side.

The large gauge wires you removed connect to the contact side to carry high current. The plug in question is for the low-current, coil side (essentially, the switch to open the relay).

So, yes secure/cover the plug, and it's best to pull fuse F42 to break the circuit so the plug never has power.

 

[ScotM]

Already been answered sufficiently, but I'll add...

The PCR is a relay so it has a contact side and a coil side.

The large gauge wires you removed connect to the contact side to carry high current. The plug in question is for the low-current, coil side (essentially, the switch to open the relay).

So, yes secure/cover the plug, and it's best to pull fuse F42 to break the circuit so the plug never has power.

Great clarification. Thanks again for all your help. It went relatively smoothly.

 

[Jebiruph]

An etorque engine always cold starts from a single 12V battery as designed by Jeep engineers, I wonder if that's damaging the computer. For etorque ESS restarts, the 12V battery doesn't crank the starter, so computer damaging 12V battery surges aren't an issue.

I will add this to my previous comment. Not everything is getting powered during a cold start. Accessories like the heater and radio are not powered during a cold start, unlike an ESS restart where everything is powered. All of the JL/JT battery systems are designed so a that an ESS restart where everything is powered involves 2 batteries, one for the electronics and one to start the engine.

Also, knowing that it's possible for an ESS component to fail and prevent the separation of batteries during an ESS event, the Jeep engineers allow for 6 ESS events from a single battery before disabling the ESS system. They evidentially must not have been too concerned about damage to the system from the 6 single battery ESS restarts.

 

[THAW]

I will add this to my previous comment. Not everything is getting powered during a cold start. Accessories like the heater and radio are not powered during a cold start, unlike an ESS restart where everything is powered. All of the JL/JT battery systems are designed so a that an ESS restart where everything is powered involves 2 batteries, one for the electronics and one to start the engine.

Also, knowing that it's possible for an ESS component to fail and prevent the separation of batteries during an ESS event, the Jeep engineers allow for 6 ESS events from a single battery before disabling the ESS system. They evidentially must not have been too concerned about damage to the system from the 6 single battery ESS restarts.

And...

a warm start (ESS restart) requires a lot less power than a cold start, so there's potentially more (stable) power even from one battery to support additional accessories/modules at proper voltage.

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