Jumperless Aux Battery Bypass

[ConqSoft]

You did disconnect the negative battery cable for the AUX battery as well when you did this, yes?

If so, wondering if you had some errant fuse that wasn't seated properly maybe when you first did it.

Yeah disconnected and taped off.

I regularly check that everything is seated and haven’t had any loose since I seated the loose ones right after delivery.

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[mdkautzman]

Well, sorry but I got nothin'. Maybe someone else can chime in.

Yeah disconnected and taped off.

I regularly check that everything is seated and haven’t had any loose since I seated the loose ones right after delivery.

Make sure you disconnected the smaller negative cable. If you already haven't.

 

[ConqSoft]

Make sure you disconnected the smaller negative cable. If you already haven't.

Yep, that’s the one. And it solved the issue of my main battery drain.

I think if I disconnected the wrong negative cable I’d have other issues.

 

[Jebiruph]

Skimmed through but didn't see anyone mention. When I pulled F42 it also crippled my Uconnect; it went into some other limited-use mode and also lost my backup camera. Started working again once I replaced the fuse.

Anyone else?

I would try disconnecting both batteries for a few minutes to power cycle everything.

 

[AirForceAngler]

Hello all! I started getting the message "AUX Switches temporarily unavailable while battery charges" a few days ago. I figured this was a sign that one or both batteries may be going bad. I followed the procedure here of removing the F42 fuse and disconnecting the Aux Neg cable. Checked the voltage on my main battery and it was 11.4 so I replaced my main battery with an H7 AGM. After all of this, I'm still getting the AUX Switches warning. New main battery is measuring 12.49 volts. Any other ideas to try to not get this message and bypass the Aux battery? Thanks!
FYI... I am running a Tazer with ESS disabled.

 

[Tagoren06]

Hello all! I started getting the message "AUX Switches temporarily unavailable while battery charges" a few days ago. I figured this was a sign that one or both batteries may be going bad. I followed the procedure here of removing the F42 fuse and disconnecting the Aux Neg cable. Checked the voltage on my main battery and it was 11.4 so I replaced my main battery with an H7 AGM. After all of this, I'm still getting the AUX Switches warning. New main battery is measuring 12.49 volts. Any other ideas to try to not get this message and bypass the Aux battery? Thanks!
FYI... I am running a Tazer with ESS disabled.

I am finding out that the 18 JL's can't do the bypass. I have tried several times with both of mine and neither worked. I was able to temporarily use a 40a fuse on N1/N2 to start it but would only last 5m or so. I believe the 18 given they are the 1st gen of the JL have either firmware or some other wiring issue with a harness. My wife's had to have a relay and harness replaced and Mine is in the shop trying to figure out what went bad.

It is frustrating that we can't just swap the batteries and be done with it. Seems like the only option is the shop or dual battery system, BUT I believe you have to have the fix done first before you go genesis dual bat. system.

I will let you know my outcome, Overall getting stupid we can do simple maintenance items without the system going stupid.

 

[AirForceAngler]

I am finding out that the 18 JL's can't do the bypass. I have tried several times with both of mine and neither worked. I was able to temporarily use a 40a fuse on N1/N2 to start it but would only last 5m or so. I believe the 18 given they are the 1st gen of the JL have either firmware or some other wiring issue with a harness. My wife's had to have a relay and harness replaced and Mine is in the shop trying to figure out what went bad.

It is frustrating that we can't just swap the batteries and be done with it. Seems like the only option is the shop or dual battery system, BUT I believe you have to have the fix done first before you go genesis dual bat. system.

I will let you know my outcome, Overall getting stupid we can do simple maintenance items without the system going stupid.

I'm going to try another bypass/delete option for the Aux battery that I found on another forum. In this case, you remove the Aux battery, connect it's Pos cable to the main and just tape up the Aux Neg cable. I'll also replace the F42 fuse as removing this wasn't mentioned in that option. We'll see! Either that or I get a new Aux battery.

 

[Rhinebeck01]

I am finding out that the 18 JL's can't do the bypass. I have tried several times with both of mine and neither worked. I was able to temporarily use a 40a fuse on N1/N2 to start it but would only last 5m or so. I believe the 18 given they are the 1st gen of the JL have either firmware or some other wiring issue with a harness. My wife's had to have a relay and harness replaced and Mine is in the shop trying to figure out what went bad.

It is frustrating that we can't just swap the batteries and be done with it. Seems like the only option is the shop or dual battery system, BUT I believe you have to have the fix done first before you go genesis dual bat. system.

I will let you know my outcome, Overall getting stupid we can do simple maintenance items without the system going stupid.

@Tagoren06

I have a 2018 JL, that was manufactured on 5/5/18 and the N1-N2, 40 amp fused bypass jumper worked well before and after, TSB 18-092-19 (Power Control Update) that changed the dual battery behavior on my 2018 JL. Been using a 40 amp fused bypass jumper for 4 yrs. and 65,000+.

Also works is.... N1 to Main positive 40 amp fused bypass jumper.

As for the "jumperless bypass" approach, I have not tried that on my JL that has had TSB 18-092-19 performed.

.

 

[Rhinebeck01]

I'm going to try another bypass/delete option for the Aux battery that I found on another forum. In this case, you remove the Aux battery, connect it's Pos cable to the main and just tape up the Aux Neg cable. I'll also replace the F42 fuse as removing this wasn't mentioned in that option. We'll see! Either that or I get a new Aux battery.

@AirForceAngler

Doing the Aux battery delete has been talked about for yrs. on this forum...

Rather then doing the delete some/most find an easier approach, is to just use an N1-N2 40 amp fused bypass jumper and then disconnecting the ESS negative cable that is connected to the Main battery neg terminal.... It is a far quicker/easier approach. With this way, leave F42 in place.

Regardless of whether you bypass or delete, DO... after doing so minimize use of the ESS feature of your JL.

.

 

[Tagoren06]

I'm going to try another bypass/delete option for the Aux battery that I found on another forum. In this case, you remove the Aux battery, connect it's Pos cable to the main and just tape up the Aux Neg cable. I'll also replace the F42 fuse as removing this wasn't mentioned in that option. We'll see! Either that or I get a new Aux battery.

Good luck might work given this is how the genesis is wired more or less. Let me know how it goes.

 

[Tagoren06]

@Tagoren06

I have a 2018 JL, that was manufactured on 5/5/18 and the N1-N2, 40 amp fused bypass jumper worked well before and after, TSB 18-092-19 (Power Control Update) that changed the dual battery behavior on my 2018 JL. Been using a 40 amp fused bypass jumper for 4 yrs. and 65,000+.

Also works is.... N1 to Main positive 40 amp fused bypass jumper.

As for the "jumperless bypass" approach, I have not tried that on my JL that has had TSB 18-092-19 performed.

.

I had an ATO 40amp fuse on it and burned up in 5 mins each time. glad it is working on yours. I had no issues with my jeep til I swapped batteries. So sounds like just my luck with this lol.

 

[Fudster]

I'm going to try another bypass/delete option for the Aux battery that I found on another forum. In this case, you remove the Aux battery, connect it's Pos cable to the main and just tape up the Aux Neg cable. I'll also replace the F42 fuse as removing this wasn't mentioned in that option. We'll see! Either that or I get a new Aux battery.

Here is my opinion on what may very well happen if you do this.

If your 2018 is one of the older ones, and doesn't have TSB 18-092-19 applied you will not be able to crank.

If TSB 18-092-19 has been applied then your first attempt at cranking will fail, but your second will attempt to crank off the main battery only. If successful, the vehicle will turn off ESS and tell you so in the EVIC.

All subsequent cold cranks will occur off the main battery but will test for the presence of an Aux battery as well. If a working Aux battery is re-cabled back into your JLs electric circuits, the next cold crank should turn off the ESS off light and restore the crank to the default factory behavior.

 

[Rhinebeck01]

I had an ATO 40amp fuse on it and burned up in 5 mins each time. glad it is working on yours. I had no issues with my jeep til I swapped batteries. So sounds like just my luck with this lol.

@Tagoren06

Many many many here use a 40 amp fused bypass jumper. Not sure why you had an issue.

I know a few guys/gals using a 20 amp fuse said they were concerned 20 was not going to be enough to handle the draw but 40 amp has done the trick for all.

In years... your post is the first forum post saying the fused 40 amp bypass jumper was a no go.

 

[Rhinebeck01]

I had an ATO 40amp fuse on it and burned up in 5 mins each time. glad it is working on yours. I had no issues with my jeep til I swapped batteries. So sounds like just my luck with this lol.

@Tagoren06

Wonder if your High Amp Fuse Array has a blown N3.... possibly blown when you did your battery swap.

 

[Fudster]

@AirForceAngler

Doing the Aux battery delete has been talked about for yrs. on this forum...

Rather then doing the delete some/most find an easier approach, is to just use an N1-N2 40 amp fused bypass jumper and then disconnecting the ESS negative cable that is connected to the Main battery neg terminal.... It is a far quicker/easier approach. With this way, leave F42 in place.

Regardless of whether you bypass or delete, DO... after doing so minimize use of the ESS feature of your JL.

.

Confused.

The fused bypass, barring no other changes to factory wiring on dual battery JLs, connects the two batteries in parallel at all times. Without the fused bypass those batteries are in parallel at nearly all times but cold cranks and ESS events(?)

But once you've disconnected the ESS negative cable that is connected to the Main battery negative terminal, in other words broken the electrical connection from the ESS battery's negative post to the Main battery's negative post, you've isolated the ESS battery. I would think then that any connection to the ESS battery's positive terminal only (a.k.a. the fused jumper connected to N1) would serve no purpose.

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