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Discussion Starter · #1 ·
Hey guys I've got a three month old 2012 Wrangler and I went to drive to work yesterday and I went to turn it on and nothing. So I tried jumping it and that wasn't working. I thought the battery was dead but I have auxiliary lights that are connected straight to the battery and they turn on. I don't know anything about working on Jeeps so Any ideas on what might be wrong?

Thanks for any help
 

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Did you have any precursor indications? The possible list is pretty wide open from the key, switches, electronics,starter, possibly still the battery even though the aux lights up because you don't have enough cranking amps ( I don't know how long you kept the cables on), etc.

You may need to get it towed in for a check.
 

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Discussion Starter · #3 ·
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
There were no precursors to this I drove it home from the night before and everything seemed normal. When jumping it I kept the cables on for about a half an hour. I plan on towing it but I figured I'd throw the problem up on here just in case I was an easier fix than I thought.
 

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Since you are stabbing in the dark what about the transmission in park switch (assuming auto). Can you go to acc and move the shifter from the position it is in? The dash lights(indicating power) would have to light up to move it from park. If not the problem is likely further back..fuse box? Did you disconnect and reconnect the battery (neg side)?
 

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Have you checked your fuses?

But, it kind of sounds to this total modern-vehicle-computer-control-stuff idiot, that you might have a bad PCM (Power Control Module)
 

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... disconnect and reconnect the battery (neg side)?
Hey, sandbaja... :wavey:

I thought that it was the positive terminal that was supposed to be disconnected??? If you disconnect the negative, any short can still go to ground, and you have to be mighty careful because everything is still live.

I learned to disconnect the positive terminal and touch it to the negative to discharge the capacitors that maintain computer memory.

Am I missing something? I wouldn't be surprised if I was....
 

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Hey, sandbaja... :wavey:

I thought that it was the positive terminal that was supposed to be disconnected??? If you disconnect the negative, any short can still go to ground, and you have to be mighty careful because everything is still live.

I learned to disconnect the positive terminal and touch it to the negative to discharge the capacitors that maintain computer memory.

Am I missing something? I wouldn't be surprised if I was....
No you are correct for the short to ground scenario however I always think that because I disconnect the neg on my baja bug when I leave Mexico. In micro electronics (5,12,24 volt) when reconnecting you want the grounds to contact first (reduced risk to components when hot swapping components). You will see this in some cable connectors with the ground lead being just slightly longer.

I think the rule is disconnect negative first and reconnect positive first but to me it doesn't make a difference as long as you are careful to not short positive to ground. The key is to break the circuit to reset components. Capacitors can retain charge for quite a while and based on the circuit design it may or may not get discharged using the scenario you describe.
 

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Great pointer Bill. There are two ways to look at this. One is safety and the other is design characteristics of a module.

In the case provided by Quadratec you are going for complete drain in resetting the ECU. The ECU on a Jeep may be designed that way but not all modules are.

For safety it is "do not be the path of least resistance(electrocution)" and "don't create a scenario where you create a spark for ignition(explosion)".. This is why you should go to frame ground when jumping a battery. There are lots of guides for this. I've linked one. I've seen two car batteries explode in my lifetime (no, they weren't mine :))



Battery Safety
 

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To be honest, I wouldn't touch it and get the dealer to fix it. It's a 2012 so I know Its got FULL warranty on it.....
 

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Who remembers the day when the engine compartment had a ton of open work space and you could take a long screwdriver and short the starter leads to get your car to start?

Not to get off track OP...hope it works out for you.Let us know the resolution.
 

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Discussion Starter · #13 ·
Well I got it to work Kinda. The problem is with one of the mini-fuses. After pulling each of them and checking to see if one was blown out, they all looked fine and for gins I tried starting it and it started perfectly. So I thought probably one of the fuses wasn't set in properly but later that night when I was leaving the bar with some friends the Jeep didn't start again. So I opened the fuse box and started pulling them again but after I checked one I hit my key-fod to see if the power was back and It would make it easy to pin-point which fuse was the problem. Sure enough I found the fuse and it started up again. So I'm going to replace that fuse.
 
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