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Discussion Starter #1
I've been having an ongoing issue with my JK just tanking while driving. I coast to the side of the road and waiting about 10 minutes and it starts again. I've been keeping track of the voltage, runs around 14.7 in the morning with lights, radio and heater going and 13.7 in the afternoon with nothing on. About once a week it will shutter a bit and the voltage will drop down to 12.2ish.and coast to a stop. When I try to start it the starter sticks on until I turn the key off. I have made sure the terminals are clean and tight, checked the wiring I can get to, replaced the battery and the alternator and it keeps happening. What am I missing? Could it be the computer going bad? Any helpful ideas would be greatly appreciated. Thanks
 

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Not sure what the issue is but the drop in voltage is normal during a stall. The alternator puts out 13 to 14.7v when the motor is running. When the motor stalls for what ever reason the alternator stops working, so the gauge starts measuring direct battery voltage which is 12ish.
 

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Discussion Starter #3
I know the voltage range, I'm trying to figure out why its dropping out. It only stalls in the afternoons on my way home from work.
 

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If its loose battery cables, your dash should light up like a xmas tree
It could be a crank position sensor. Mine did something similar, stuttering a lot and only in the afternoons on the way home from work. Never did die completely though. Its a $15 part and 10 minutes of your time to replace, so couldnt hurt to try
 

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Discussion Starter #8
If its loose battery cables, your dash should light up like a xmas tree
It could be a crank position sensor. Mine did something similar, stuttering a lot and only in the afternoons on the way home from work. Never did die completely though. Its a $15 part and 10 minutes of your time to replace, so couldnt hurt to try
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That's the weird thing, no dash lights at all. It just coasts to a stop. Then won't start for about 10 minutes. The starter cranks but won't catch or stop until I turn the key to off. I can try replacing the crank sensor just to eliminate one more variable. Thanks for the suggestion.
 

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That's the weird thing, no dash lights at all. It just coasts to a stop. Then won't start for about 10 minutes. The starter cranks but won't catch or stop until I turn the key to off. I can try replacing the crank sensor just to eliminate one more variable. Thanks for the suggestion.
Sounds to me like either the security system is shutting the jeep down (stops recognizing the chip in the key for a time), or perhaps a fuel faulty fuel pump.

I don't see the cranking being an issue. The jeep has "auto cranking" (I'm not sure if that's the exact term). You don't have to hold the key while it's cranking. Once you turn the key you can let go and the computer continues the crank until it senses a start, so something is actively blocking the motor from starting. The "10 minutes" makes me think it has something to do with security, or a temporarily overheated fuel pump.... or something similar.
 

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I had a slightly loose negative battery terminal a couple years ago that was causing me some issues. Once I spent $90 for the dealer to tell me they could not replicate my problems, and I did some searching here, I fixed it quick.
 

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Discussion Starter #11
Sounds to me like either the security system is shutting the jeep down (stops recognizing the chip in the key for a time), or perhaps a fuel faulty fuel pump.

I don't see the cranking being an issue. The jeep has "auto cranking" (I'm not sure if that's the exact term). You don't have to hold the key while it's cranking. Once you turn the key you can let go and the computer continues the crank until it senses a start, so something is actively blocking the motor from starting. The "10 minutes" makes me think it has something to do with security, or a temporarily overheated fuel pump.... or something similar.
Thank for the ideas, I hadn't even thought of the security system. I was thinking it could be the IDrive I have installed causing the problems so I set it to normal which is factory settings and my volts are now much closer to normal. I read that other brands of throttle controllers caused the throttle to just shut down so I'm giving it a try. It would be a simple fix after several months of frustration. Time will tell. I'll look into the security system if it continues.
 

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I had a slightly loose negative battery terminal a couple years ago that was causing me some issues. Once I spent $90 for the dealer to tell me they could not replicate my problems, and I did some searching here, I fixed it quick.
Thanks for responding. I tightened down the terminals as tight as I could but decided to buy better quality solid terminals to replace them. We'll see if it helps.
 

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Discussion Starter #13
Thank for the ideas, I hadn't even thought of the security system. I was thinking it could be the IDrive I have installed causing the problems so I set it to normal which is factory settings and my volts are now much closer to normal. I read that other brands of throttle controllers caused the throttle to just shut down so I'm giving it a try. It would be a simple fix after several months of frustration. Time will tell. I'll look into the security system if it continues.
Update: My jeep was dying once a week every week for months. I set my IDrive to factory settings and have made it thru just over a week without dying and the volt are more in the normal range but still not where it should be. I haven't disconnected the IDrive just yet, waiting a few more weeks to be sure it's the culprit.
 
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