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Discussion Starter #1
Hi All,

Last night my wife's 2007 Jeep Commander Limited 4.7 Flex-fuel wouldn't start after the dashboard battery light came on prior. So I jumped it with cables - and got it home.

I bought and installed a new battery, it started right up.

I turned it off, then noticed the alternator was abnormally hot, then it started smoking. I disconnected the battery, and left it disconnected over night.

I bought a new rebuilt alternator this morning and installed it, reconnected the battery. Then I tried to start it, engine turns over , but doesn't start up.

Any help is appreciated! :)

Also, Happy Thanksgiving all!
 

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Normally I'd jump straight to suggesting you look @ the yellow starter wire that corrodes on the connection to the starter. However this sounds like another problem that I am not familiar with. :icon_confused:
 

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Discussion Starter #5 (Edited)
Update:

Hope everyones Thanksgiving was awesome! I went out Thanksgiving morning to have another look at the Commander. I checked all fuses, and all seem to be fine.

I checked dash code and nothing. I figured what the heck - I pulled the Fuel Pump Relay, and tried to start the jeep. To my surprise it started and a couple seconds later shut down! plugged the relay back in and tried to start again, it just turned over but didn't start. Pulled the relay again, and tried to start. It started and ran rough, I quickly plugged in the relay an got in the drivers seat to hit the gas pedal. It kept running rough for a few seconds, then settled down and ran smooth!

:D

I took it down the street, ran fine. Went for a test drive , and all is well!

Thanks!
 

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Update:

Hope everyones Thanksgiving was awesome! I went out Thanksgiving morning to have another look at the Commander. I checked all fuses, and all seem to be fine.

I checked dash code and nothing. I figured what the heck - I pulled the Fuel Pump Relay, and tried to start the jeep. To my surprise it started and a couple seconds later shut down! plugged the relay back in and tried to start again, it just turned over but didn't start. Pulled the relay again, and tried to start. It started and ran rough, I quickly plugged in the relay an got in the drivers seat to hit the gas pedal. It kept running rough for a few seconds, then settled down and ran smooth!

:D

I took it down the street, ran fine. Went for a test drive , and all is well!

Thanks!
Interesting! Glad it seems to be working. :icon_cheers:
 

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First I'd replace that relay. 2nd, I'd test the voltage
at the battery while the Jeep is running to make sure
it read's between 13.6-14.2 volts. 13.8 is ideal, but
it can fluctuate depending on the amperage draw... 0.02
 

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Actually the Charging voltage will vary based off the temperature, the colder it is, the higher the voltage.

On my voltmeter, a Autometer gauge on the dash, I read 13.5V in the summer, and 14.8V in Winter below freezing.
 

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Correct, there are variables. Just want to make sure
it's charging. Should be reading 13+ volts...
 

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Just to add, 13+ Volts is the critical number. For the battery to charge, the charging system, basically the whole electric systems, voltage has to be higher than the battery voltage. If the voltage for the charging/electric system is lower than the battery, than the battery will take up the slack and provide voltage/current, and drain the battery.

The Battery is 12VDC nominally, a fully charged battery in tip top condition might show 13VDC and the voltage drops off as it drains.

So, like 99XJ says, if the Charging/Electric system shows 13+ volts that means it must be charging the battery.

Also check the voltage engine off and engine running (i.e. just battery vs alternator supplying power), the charging/electric system voltage should always be higher than the battery in all cases, or you have a problem.

The battery looking warning light on the dash, is really a charging/electric system fault warning light. They make the light like that for the typical idiot consumer, because all they can understand is that the battery is likely going to go dead.

Typically, the figures may be different for the Commander, but close, it goes off if the voltage is too low or high, or the PCM recognizes that field control of the alternator is NOT working right (which the most likely cause of that is a bad alternator and will result in voltage being to high or low). Typically volts drop below 9VDC or above 15VDC it will set off the light. If you charging/electric system drops below 9VDC, your alternator is NOT supplying enough current (there can be all sorts of causes for that, including things that can happen with a perfectly good alternator) and the battery is draining very quickly.

If the light stays on because of low voltage you only have a 10-30 minutes before the car will go dead (depending on the electric load on the battery, i.e. headlights) and the battery may be too drained to restart the motor. Sounds like that is exactly what happened to you.
 
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