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18 JLU No Start/No Crank

LewsWorld757

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HERES MY SITUATION:
I’m stomped here, in my 18 Wrangler JLU, V6 3.6L, I had to change out the main battery cause the AUX battery killed it, I was hoping the main battery would charge the AUX battery, but the AUX Battery killed my main battery again, I put in a new AUX battery and charged the the main battery, I re installed everything and all connections are secured and good, and checked the PDC and no fuses are blown, I have a no start/no crank Situation, but I am getting power to the inside of the Jeep, (lights work, panels illuminate, and get braking lights), both batteries were giving 12 Volts at the time, I tried an AUX battery bypass to try to start the Jeep and this was a NO GO, I disconnected the main battery and start up the Jeep with the AUX battery and that was a NO GO. I disconnected all batteries and hooked up a 1400 CCA Jump Box, and still a NO GO. Each test is showing that I am getting power to the inside of the Jeep but I’m assuming I’m not getting power to my engine. I was told to test my High Fuse Amp, But this is where the plot twist comes in, my main battery is dead again, I am unable to properly test the High Fuse Amp. It also seems like I’m not getting power to my ignition switch or Radio.

CONCLUSION:
I’m looking to make sure I’m covering all my P&Qs, I know I need to replace the main battery, I’ve been told I should test the starter and alternator too (even though I’m not sure what that has to do with this certain situation), with all my reading/research I’ve done it is pointing to the High Fuse Amp, but I haven’t found a situation like mine, and I’m completely lost at this point.

Jeep Wrangler JL 18 JLU No Start/No Crank 79F85180-99C1-4641-A997-5316629AE2C6


Jeep Wrangler JL 18 JLU No Start/No Crank 5348C7F1-6C6B-4CED-84F3-E0440D58FD2E


Jeep Wrangler JL 18 JLU No Start/No Crank 9DF3B1DF-8730-4700-8F46-0AC30A37D323




Jeep Wrangler JL 18 JLU No Start/No Crank C40AEC18-691C-4A24-A51D-67C4C2DD5F4E
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aldo98229

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Welcome to the forum.

Recently a fellow forum member had this same issue.

He checked all his connections and discovered that he had bent one of the pins in the fuse box connectors when he replaced the batteries. He straightened out the pin and his Jeep started right up.

Good luck.
 

txj2go

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I don't know why the batteries are affecting each other. It sounds like you have a fuse problem to me, you would have to use a volt-ohm meter to test your big fuse to see if one of the parts has been affected.
You can operate without the small battery, depending on the version of engine control software in your 2018. The original software would require that you add a jumper in the fuse block, there are lots of threads here about doing that. If your vehicle has had updated software then you can just remove the small battery and go on about your business.
 

jaymz

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I see a bit of aftermarket wiring. Have you made sure 100% that that isn’t the problem?
 
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LewsWorld757

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The after market wiring are for my 6 LED Lights, and winch, I wouldn’t think that would be causing this no start.
 

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LewsWorld757

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Thank you for the input, I checked all of those prongs also, cause that was the first thing that came to mind that I could of bent something but everything is intact nothing is bent.
 

Midwestjeepguy

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HERES MY SITUATION:
I’m stomped here, in my 18 Wrangler JLU, V6 3.6L, I had to change out the main battery cause the AUX battery killed it, I was hoping the main battery would charge the AUX battery, but the AUX Battery killed my main battery again, I put in a new AUX battery and charged the the main battery, I re installed everything and all connections are secured and good, and checked the PDC and no fuses are blown, I have a no start/no crank Situation, but I am getting power to the inside of the Jeep, (lights work, panels illuminate, and get braking lights), both batteries were giving 12 Volts at the time, I tried an AUX battery bypass to try to start the Jeep and this was a NO GO, I disconnected the main battery and start up the Jeep with the AUX battery and that was a NO GO. I disconnected all batteries and hooked up a 1400 CCA Jump Box, and still a NO GO. Each test is showing that I am getting power to the inside of the Jeep but I’m assuming I’m not getting power to my engine. I was told to test my High Fuse Amp, But this is where the plot twist comes in, my main battery is dead again, I am unable to properly test the High Fuse Amp. It also seems like I’m not getting power to my ignition switch or Radio.

CONCLUSION:
I’m looking to make sure I’m covering all my P&Qs, I know I need to replace the main battery, I’ve been told I should test the starter and alternator too (even though I’m not sure what that has to do with this certain situation), with all my reading/research I’ve done it is pointing to the High Fuse Amp, but I haven’t found a situation like mine, and I’m completely lost at this point.

79F85180-99C1-4641-A997-5316629AE2C6.jpeg


5348C7F1-6C6B-4CED-84F3-E0440D58FD2E.jpeg


9DF3B1DF-8730-4700-8F46-0AC30A37D323.jpeg




C40AEC18-691C-4A24-A51D-67C4C2DD5F4E.jpeg
Did you figure this out? I’m going through this exact scenario right now and troubleshooting everything. No luck so far.
 

Sdchrisc

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Have the same issue.. anyone find a fix?
 
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LewsWorld757

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Have the same issue.. anyone find a fix?
It was the high fuse amp. but I am currently experiencing the same problem again, and also ran into an over charging problem once that fuse was changed it compromises the safety mechanisms designed to protect against over-current conditions. In conclusion that fuse going bad is a common occurrence in these newer Jeeps specially the 4XE.

heres a good video breaking stuff down.
 
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LewsWorld757

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Did you figure this out? I’m going through this exact scenario right now and troubleshooting everything. No luck so far.
It was the high fuse amp. but I am currently experiencing the same problem again, and also ran into an over charging problem once that fuse was changed it compromises the safety mechanisms designed to protect against over-current conditions. In conclusion that fuse going bad is a common occurrence in these newer Jeeps specially the 4XE.
 

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mwilk012

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It was the high fuse amp. but I am currently experiencing the same problem again, and also ran into an over charging problem once that fuse was changed it compromises the safety mechanisms designed to protect against over-current conditions. In conclusion that fuse going bad is a common occurrence in these newer Jeeps specially the 4XE.
fuses don't go bad, and it isn't a common occurrence. it is 100% caused by user error when moving battery cables around.
 

Sdchrisc

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Random no starts.. battery constantly charging at 14.5v when running.. is there a way to test if the ibs sensor is bad?
You have what same issue, your Jeep won't start?
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