Jumperless Aux Battery Bypass

[Sturtzy]

If you have an aux battery, yes.



Yes, pull fuse F42 and disconnect the aux cable from the main negative terminal. It should be the skinnier of the 2 cables connected to the terminal.

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[Sturtzy]

If you have an aux battery, yes.



Yes, pull fuse F42 and disconnect the aux cable from the main negative terminal. It should be the skinnier of the 2 cables connected to the terminal.

Which cable is for the aux. Battery?

 

[Rhinebeck01]

Which cable is for the aux. Battery?

Smaller diameter cable is Aux negative cable.

 

[Sturtzy]

Smaller diameter cable is Aux negative cable.

Seem to me to be the same diameter. Left or right one?

 

[Sturtzy]

Viewing on smartphone ... hard for me to see diameters. What year is your JL?

2019.
I unhooked the left one and here's what it did
2 tries with start button then started
Power steering light came on
Traction controll light on
And 1 other light maybe for suspension?
Auto start light on still??

 

[andy29847]

MY 2020 - aux cable disconnected and tied back

I unhooked the left one and here's what it did
2 tries with start button then started
Power steering light came on
Traction controll light on
And 1 other light maybe for suspension?
Auto start light on still??

I'm wondering about the condition of your main battery. I haven't read all of your post so I do not know what brought you to this thread.

 

[JOMOjl]

Really hoping I don’t jinx myself but here goes.
I removed my aux battery about a month ago. I went in through the top because I didn’t want to mess with the fender liner. Plus I was going to have to pull the positive lead up anyway.
Disconnected both leads, taped off the negative, reassembled the fuse box, and added the positive lead from the aux to the main. Battery was near 3 years old so I got a bigger battery to replace the main. Tazer keeps my ESS off. No problems. Shows 14 on the dash.

 

[Sturtzy]

MY 2020 - aux cable disconnected and tied back

I'm wondering about the condition of your main battery. I haven't read all of your post so I do not know what brought you to this thread.

I just got the jeep a couple weeks ago and its been fine. The battery is an Interstate. I need to get my main battery tested and start from there I think. Gauge on dash says 14.1 v at idle.

 

[Sturtzy]

MY 2020 - aux cable disconnected and tied back

I'm wondering about the condition of your main battery. I haven't read all of your post so I do not know what brought you to this thread.

Battery tested good.

 

[Rhinebeck01]

2019.
I unhooked the left one and here's what it did
2 tries with start button then started
Power steering light came on
Traction controll light on
And 1 other light maybe for suspension?
Auto start light on still??

On your 2019, the smaller diameter, Aux negative cable is the cable closest to you on the Main's negative terminal when you lean over and reach in over the passenger side fender.

Did you pull Fuse F42 ?

 

[Sturtzy]

On your 2019, the smaller diameter, Aux negative cable is the cable closest to you on the Main's negative terminal when you lean over and reach in over the passenger side fender.

Did you pull Fuse F42 ?

Yes
I'm going to try it again. I'll let you know what happens. Thanks for the help!

 

[Rhinebeck01]

Yes
I'm going to try it again. I'll let you know what happens. Thanks for the help!

 

[andy29847]

Battery tested good.

Battery tested good can be a trap. Our Jeeps seem to go funky when the battery gets around 12.4v. 12.4 is a good test for most batteries (50-70% life). With the aux negative unhooked, and after the Jeep has been sitting for a couple of hours, set it to run without starting it (on my Jeep, with the proximity key, I press the start button without putting my foot on the brake. The first press should go to aux, the second should go to run). Check the voltage display on your dash voltmeter. Answer back with your findings.

 

[Heimkehr]

Battery tested good.

Resting voltage can be OK when it's tested in isolation. What you may consider doing is observing the battery's voltage when cranking the engine. Knowing the latter number when there's a load demand on the battery will provide the necessary context about its actual health.

 

[Sturtzy]

Battery tested good can be a trap. Our Jeeps seem to go funky when the battery gets around 12.4v. 12.4 is a good test for most batteries (50-70% life). With the aux negative unhooked, and after the Jeep has been sitting for a couple of hours, set it to run without starting it (on my Jeep, with the proximity key, I press the start button without putting my foot on the brake. The first press should go to aux, the second should go to run). Check the voltage display on your dash voltmeter. Answer back with your findings.

Removed fuse and cable again and here's the results
Auto start light on still
No others on this time.
Voltage on dash reads 13.9

Put fuse/cable back and drove about an hour. Voltage at 13.4 (which I know is low)
Auto s/s light on. Don't have a meter to double check voltage. Will have a meter tomorrow to check more. Thanks again

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