HELP! 2021 JLU Wont Start!

[JeepFiend]

Another thing you try is to pull both cables off the battery, touch the positive cable to the negative cable for 10 seconds or so to try and clear the computer.

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[jbennett_418]

Another thing you try is to pull both cables off the battery, touch the positive cable to the negative cable for 10 seconds or so to try and clear the computer.

I dont think I can do that since it has the secondary battery mounted under the Jeep. I’d be worried that touching the 2 cables together would fry something due to still having power from the other battery.

 

[Omotose]

What about the neutral switch in the transmission? If you hit the dead spot it won’t start. Put the transmission in neutral and it should start right up.

 

[jbennett_418]

What about the neutral switch in the transmission? If you hit the dead spot it won’t start. Put the transmission in neutral and it should start right up.

I have tried that as well. That still wouldn't explain the power loss (No headlights, dash lights, dome lights, etc. It only has power / lights once it is hooked up to jumper cables. I had had the neutral safety switch go bad on another Jeep (98 XJ) and everything still functioned fine other than having to put it in neutral to get it to start.

 

[jbennett_418]

I disconnected all of the accessories (Winch and rock lights) from the battery to see if something was potentially causing the issue. Still nothing. No power whatsoever unless hooked to jumper cables. Once hooked to jumper cables, all lights function, but when attempting to start it, it just clicks one time. No crank, nothing more than one loud “click”.

 

[MoHeTow!]

Sounds like a loose connection somewhere

 

[jbennett_418]

I called Jeep customer support. I didnt go into the call with very high expectations so thankfully I'm not surprised or disappointed. She gave me the phone number for roadside assistance, gave me the name and contact info for the local dealer and wished me luck…

 

[MoHeTow!]

Battery cables Loose?

 

[jbennett_418]

Battery cables Loose?

I have had the battery terminals off and on again about 5-6 times per side throughout all of this. They’re 100% tight. Ive also made sure that the N1-N8 posts inside the fuse panel were tight.

 

[jbennett_418]

After spending all afternoon triple checking all of the fuses, connections, etc. I took the battery out and went to Autozone for a replacement. It started right up… Bad cell in the battery I guess? It tested fine for me. Autozones tester showed that it was bad. Im relieved and confused all at the same time…
Newest issue is that a lot of the apps are gone. The forward/rear facing camera apps, offroad pages app, climate control, etc. are all gone. I read on another page that they will reload by themself after a little while? Im gonna go out and check in about an hour to see if they’re back.

Thanks to everyone that gave tips / advice. I wish I would have tried to replace the battery earlier today and saved myself 6 hours of pointless diagnostics…

 

[areuriding]

The MOPAR batteries are junk.

 

[MoHeTow!]

The MOPAR batteries are junk.

Glad you figured it out! Good Job!

 

[jbennett_418]

The MOPAR batteries are junk.

Thats what ive been reading… I might see if the dealership will warranty the battery and then ill at least have a spare incase this BS happens again.

 

[Blanco Willys]

*Update

I tested the battery with the battery cable still attached. It was only reading 5.15 V. To confirm no error occurred, I hooked up the volt meter to a known good battery in a different vehicle and it tested at 12.58. I disconnected the battery cables from the Jeep and tested the battery again. It tested fine this time and had 12.56V.

Pictures included below :
*1st photo - Original Jeep battery test.
*2nd photo - Separate vehicle to confirm tester operation.
*3rd photo - Jeep with cables disconnected / testing battery.

If you start it with the extra battery and see 14.1 you’ll know it’s not the alternator. I’m putting money on bad cell. Winter months bring out the bad in batteries.

 

[Megawatt]

If you start it with the extra battery and see 14.1 you’ll know it’s not the alternator. I’m putting money on bad cell. Winter months bring out the bad in batteries.

So does hot desert Summers out here in Vegas. Motorcycle, truck, Ford, Honda, VW. All vehicles I have owned out here in the desert only last a guaranteed two years. After 2 it’s on borrowed time.

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