JL won’t start nor jump start

[Joe81]

2018 3,6 L manual.
When the weather started to be cold ( I think this might be the cause), I had some difficulty starting it. Then I had to jump start it every morning.
I changed the 2 batteries and it kept not starting nor jump start.
Tuesday evening, it won’t start. I charged the auxiliary battery then the main battery and it won’t start nor jump start (I use a Noco GBX155). I had to tow it to the dealership. Wednesday morning, they had no problem starting it (to my big frustration).
The dealership found a fuse of the electric sway bar disconnect in place and leaking 1,3 amp (I don’t have a sway bar disconnect ). They removed the fuse and the energy leak is gone.
When I went to the dealership Thursday morning, it was starting well, same yesterday. One it’s cold this morning (again I suppose it might be the reason but I’m not an expert), it won’t start and I can’t even jump start it.
Battery yesterday and before yesterday was 14,4 volts. This morning 12,1.
Any suggestions about the problem and how to fix this?
thank you!

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[Heimkehr]

My guess is that an unresolved parasitic load still remains on the vehicle.

 

[Dyolfknip74]

My guess is that an unresolved parasitic load still remains on the vehicle.

He's local, he shook fuse box and got it started. Doesn't explain why it needed to be boosted daily since battery change though, no?

 

[Terrymo]

…Battery yesterday and before yesterday was 14,4 volts. This morning 12,1.…

Under what circumstances did you see 14.4 volts? If you are looking at battery voltage on the dash while driving, that is your alternator output.

If after the vehicle sits for a while (to eliminate any surface voltage) with your foot off the brake and without starting the engine, you put the vehicle in the run position, look at the battery voltage on the dash. What does it show?

After driving your vehicle let it sit for a couple of hours and check the battery voltage at the battery with a multimeter. Let the vehicle sit overnight and without starting it, check the battery voltage at the battery again with a multimeter. A big drop in voltage could indicate parastic drain. This will give you a more accurate picture of what is happening.

Some more battery savvy folks should be along soon to give you better advice and correct my terminology.

 

[alphawolff]

Energy leak. That's a new term. I dig it. You might just have a bad jump box in additional to a parasitic draw, but just incase try this:

The next time this happens, try jumping the vehicle from the N3 stud of the PDC (The z-case fuse array at the far end of the fuse box). I've seen partially blown fuses cause this issue. If that N3 fuse is blown trying to jump start the vehicle from the primary battery won't work, as the interior gets power through that fuse.

You can also just remove the fuse array and test them with a multimeter while wiggling them to see if resistance jumps. They shouldn't wiggle.

 

[Joe81]

Energy leak. That's a new term. I dig it. You might just have a bad jump box in additional to a parasitic draw, but just incase try this:

The next time this happens, try jumping the vehicle from the N3 stud of the PDC (The z-case fuse array at the far end of the fuse box). I've seen partially blown fuses cause this issue. If that N3 fuse is blown trying to jump start the vehicle from the primary battery won't work, as the interior gets power through that fuse.

You can also just remove the fuse array and test them with a multimeter while wiggling them to see if resistance jumps. They shouldn't wiggle.

I meant parasitic draw. I was just making a literal translation from French using the term my mechanic used.

 

[Joe81]

Update, I’ve just shook the fuse box and it started. I tightened all the screws and will see how things will go.

 

[alphawolff]

Update, I’ve just shook the fuse box and it started. I tightened all the screws and will see how things will go.

Replace the z-case fuse.

 

[dsgrey]

Son had a similar issue on his new-to-him Honda this past week where it would take several tries before the push button starter would engage. He finally texted me when it wouldn't start at all. We found a loose wire in the harness. Wiring and fuses CAN cause issues you described.

 

[Notgeowild]

We got maybe 3 rows (about 25 deep per row) of Wrangler won't start at work.

Been sitting forever batteries left the chat

Dont get me started with Grand Cherokee's and Wagoneers.

 

[Joe81]

Replace the z-case fuse.

update. This morning it won’t start. I shook the fuse box again but won’t start. Do you think this is the Z-case?
battery voltage this morning is 12.1
I’m sure there is no more parasitic leak as the dealership told me it’s 0.01 amp as it should normally be.

 

[Terrymo]

update. This morning it won’t start. I shook the fuse box again but won’t start. Do you think this is the Z-case?
battery voltage this morning is 12.1
I’m sure there is no more parasitic leak as the dealership told me it’s 0.01 amp as it should normally be.

As you probably know that’s a very low state of charge. Maybe it’s worth trying the suggestion of @AlphaWolf

 

[VKSheridan]

Joseph, when you say it doesn’t start, what does it do? Do you hear a single tick of the starter bendix kicking in, repeated ticks or is there zero noise? Does the dome light dim or go out, does it always start once warm or started once or are there any other observations you can share?

New batteries connected to a NoCo maintainer should be able to carry a nominal parasitic drain unless you’re parking with sodium quartz flood lights turned on and running your winch to mine coal.

I’m thinking it might be something simpler like your starter bendix. If it picks up crud, sometimes the bendix coil just doesn’t have enough strength to pull them in and close the contact plate in when it’s cold. Once the greasy crud warms, it behaves.

 

[aeonixx1001]

He's local, he shook fuse box and got it started. Doesn't explain why it needed to be boosted daily since battery change though, no?

I would check all your connections, they probably pulled one loose when changing battery

 

[Joe81]

update. This morning it won’t start. I shook the fuse box again but won’t start. Do you think this is the Z-case?
battery voltage this morning is 12.1
I’m sure there is no more parasitic leak as the dealership told me it’s 0.01 amp as it should normally be.

Joseph, when you say it doesn’t start, what does it do? Do you hear a single tick of the starter bendix kicking in, repeated ticks or is there zero noise? Does the dome light dim or go out, does it always start once warm or started once or are there any other observations you can share?

New batteries connected to a NoCo maintainer should be able to carry a nominal parasitic drain unless you’re parking with sodium quartz flood lights turned on and running your winch to mine coal.

I’m thinking it might be something simpler like your starter bendix. If it picks up crud, sometimes the bendix coil just doesn’t have enough strength to pull them in and close the contact plate in when it’s cold. Once the greasy crud warms, it behaves.

I hear 2 consecutive ticking sound as if coming from the engine to the battery to the fuse box and that’s it. The lights turn on and the dashboard turns on. When I get out, the lights turn off normally.

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