I would have said alternator too

Reading this, it was a very similar to the gremlin I had. There is no dealer around here that will work with me, so I am on my own.

I think the first culprit was the radiator fan relay that started it all.

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2002 KJ Limited 3.7
Completely Stock
215/85R16 Kevlar

That was our biggest fear, that they were just going to give up and return it us.

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2005 Liberty Sport
Bright Silver
Automatic
Sunroof
Reese 2" Class 3 Hitch for towing the sleds.

Any new developments? I replaced my betteryou, then a month later my alternator about a year ago and now the battery light comes back on. I put a meter on it and to cranks out 14 v high rev and holds 12 after sitting.

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2002 KJ Limited 3.7
Completely Stock
215/85R16 Kevlar

The early Kjs have a Battery Temperature Sensor located under the battery. This senses the battery temperature and accordingly causes the PCM to adjust the charging rate.

If the sensor fails it will also set the Battery Light. If possible, get the codes read out or use the "Key" trick...this could pull up battery temp. sensor codes so you know your problem is in that area. If so, pull out the sensor and measure the resistance of it with an Ohmeter...it should read about 2,000 Ohms at room temperature. Place the sensor on a light bulb...the resistance should fall down to about 200 Ohms as it heats up.

If you still have battery temp. sensor codes after replacing sensor...check the wiring hoing to the PCM...one wire is supposed to go to ground...add an extra ground if needed and the other goes to the PCM connector ...try re-plugging the connectors on the PCM.

You can download the relavant year Service Manual here...includes circuit diagrams: http://www.colorado4wheel.com/manuals/Jeep/KJ

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2002 Export CRD 2.5 Sport

Thanks, I'll check that. I actually have one of those readers with a "Torque" app on my phone. I didn't check the codes because the check engine light is on due to a bad downstream oxygen sensor.

I have the sensor, but I am wary of the clip which doesn't seem to want to come off. I also have the manual. Guess I'll have to break that out and send a weekend with my truck.

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2002 KJ Limited 3.7
Completely Stock
215/85R16 Kevlar

So, after sitting outside at near freezing temperatures the battery still had over 12v in it and it fired right up. The battery light is out but now I have a new code, the dreaded P1491. I say dreaded because that was the code it threw two years ago when I got it and after replacing the relay and and a few other parts, the problem was resolved when I tore the plastic covering off of the Power control center and cleaned up all the contacts.

I guess new tires are going to have to wait unit I make sure this isn't going to be something like the computer.

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2002 KJ Limited 3.7
Completely Stock
215/85R16 Kevlar

I guess you can't trust batteries nor alternators anymore. Trusted rebuilder and a glass battery and no problems since.

_________________
2002 KJ Limited 3.7
Completely Stock
215/85R16 Kevlar