Battery light came on

[Sassy0876]

I was driving home from work today and I heard a ding liked down and my battery light was on. Jeep still ran fine wipers, radio all worked. Got home let it idle in the driveway and all was good. Turned the ac on and it worked. Shut car off and started it back up. Started up with no problems no lag or anything and battery light is off now. I am fixing to drive 800 miles one way tomorrow and I am now scared something is wrong. I will be driving at night and my hubby will be with me any advice? It is an 02 liberty sport 3.7 4x4.

 

[jeeplib05]

I was driving home from work today and I heard a ding liked down and my battery light was on. Jeep still ran fine wipers, radio all worked. Got home let it idle in the driveway and all was good. Turned the ac on and it worked. Shut car off and started it back up. Started up with no problems no lag or anything and battery light is off now. I am fixing to drive 800 miles one way tomorrow and I am now scared something is wrong. I will be driving at night and my hubby will be with me any advice? It is an 02 liberty sport 3.7 4x4.

Not sure what would cause that
My guess is if everything works like normal, don't worry about it
Something small could've just made the light come on for whatever reason, electronics can be weird sometimes
You could disconnect the negative cable for a couple seconds then reconnect for reassurance, I've done the same when a random fault code came up one time and never saw it again !
But in all honesty, I wouldn't worry about it too much

 

[Jbergun]

If you had alot of accesories on and you battery or alternator is older it coukd have dropped a hair too low and set it off. If you want to be safe check your voltage when off the turn it on and check. Should be like 12.0-12-5 when off and 13.0-13.7 when on from my experience.

 

[uss2defiant]

just stop by an autopart store to get your battery and alternator tested.

 

[jeeplib05]

If you had alot of accesories on and you battery or alternator is older it coukd have dropped a hair too low and set it off. If you want to be safe check your voltage when off the turn it on and check. Should be like 12.0-12-5 when off and 13.0-13.7 when on from my experience.

I agree
I had only a couple things hooked up to my old battery and it died on me quite a bit
Put in a duralast gold and now with all of the stuff I have it never dies on me and I have free replacements for years :gr_grin:

 

[Sassy0876]

I had the ac on but that's it. But I turned the wipers on and the lights to see if they were sluggish but they werent. I'm hoping it's nothing I got a long ride ahead of me tomorow night!!! Maybe I will swing by auto zone tomorrow to get it checked out.

 

[Billwill]

I had the ac on but that's it. But I turned the wipers on and the lights to see if they were sluggish but they werent. I'm hoping it's nothing I got a long ride ahead of me tomorow night!!! Maybe I will swing by auto zone tomorrow to get it checked out.

Get the battery and Alternator tested, make sure the battery connections are clean and tight.

If the above items are OK then bear in mind that the early KJs like yours has a Battery Temperature Sensor sitting underneath the battery. This senses the temperature of the battery and make minor changes to the charging rate.

If this sensor is faulty or has a bad connection then it turns on the exact same Red Battery light as a bad alternator or battery would do!

If the battery and its connections are OK and the Alternator checks out OK and the Red light still comes ON then get back to us here and we can check out the Battery Temperature Sensor...which is not a critical component...ie. it will not cause you to grind to a halt!

 

[renegade 04]

The best way to see if you jeep is charging would be to see the voltage running and when the jeep is off. The voltage when on should be 13.8 to 14.5. Also remember that in the summer the jeep will be charging near 13.8 to about 14 volts. Post your findings.

 

[tjkj2002]

The alternator can not be correctly tested in a KJ(or almost any Chrysler) without the use of the DRBIII/starscan scanner(or high end scanner like most high end snap on scanners).

The alternator is controlled by the PCM,the voltage regulator is in the PCM.Without being able to turn on/off said regulator inside the PCM you can not properly test the charging system.


You have a issue with the charging system if the battery light has come on.Just because nothing is acting up right now does not mean there is not a problem.A fully charged battery will operate the vehicle without the alternator for a day or 2 depending on electrical load(night driving is a much higher load).

 

[CactusJacked]

I've had symptoms like that before (on a different vehicle) with the "hit & run" charging glitch. Unknown to me at the time, one of the bearings in my alternator was starting to go, the pulley would stop or slow down momentarily enough to trigger the battery light. I too thought "hmm must be an electrical issue or hiccup". The alternator finally completely locked up and left me stranded during a road trip. I would remove the serpentine belt, twirl the alternator pulley by hand, and see/hear/feel what condition the bearings are in. If the alternator is noisy, or the pulley feels like it's turning rough, then replace it.

 

[Sassy0876]

Went to auto zone to have tested battery is good but alternator is only pushing 11 volts 12 at times so gotta buy a new one the light came back on when I started going fast at least it will be fixed thank you all for your help

 

[Sassy0876]

Scratch that, when he tested the alternator it was saying voltage regulator was bad. I went back to get the alternator and they told me it wasn't the problem and that I need a new computer which is gonna cost $300. So now I guess it will sit for awhile and hopefully my ford truck is ok to take on this trip or we ain't going, I am so pissed off right now I'm ready to sell my jeep!!!

 

[tjkj2002]

Scratch that, when he tested the alternator it was saying voltage regulator was bad. I went back to get the alternator and they told me it wasn't the problem and that I need a new computer which is gonna cost $300. So now I guess it will sit for awhile and hopefully my ford truck is ok to take on this trip or we ain't going, I am so pissed off right now I'm ready to sell my jeep!!!

Go to the dealer and get your charging system checked properly.yeah it'll cost you $100+ but it's worth it to actually know what is the real issue.

 

[CactusJacked]

Scratch that, when he tested the alternator it was saying voltage regulator was bad. I went back to get the alternator and they told me it wasn't the problem and that I need a new computer which is gonna cost $300. So now I guess it will sit for awhile and hopefully my ford truck is ok to take on this trip or we ain't going, I am so pissed off right now I'm ready to sell my jeep!!!

Or keep the computer and install an external regulator bypass kit that only costs $65....provided that is what's wrong with yours. It's an issue that's popular enough for them to have made a fix for that: http://store.alternatorparts.com/hd-external-voltage-regulator-conversion-field-replacement-kit.aspx

 

[Billwill]

Make sure the battery connections are clean and tight, the negative battery lead going to chassis is clean and tight and the two grounding straps that ground the engine to the chassis is clean and tight both ends...this is the ground for the alternator so it is important.

As stated, the Alternator does not have the regulator built in...this is done by the PCM on the Driver's side of the engine bay. Disconnect the battery and re-plug the connectors on the PCM and the alternator....the alternator has one small two wire plug and a thick wire bolted onto a stud...make sure this stud connection is clean and tight.

Check that this thick lead going from the alternator to the battery is not rubbing on any engine part on its way to the battery.

I would replace the alternator before messing with the PCM...the bearings could be seizing or the brushes taking power to the field coils could be worn out or a diode in the diode pack inside the alternator could have blown. If this is the case then replacing the PCM or fitting an external Regulator will not help!

Maybe the Battery Temp Sensor in your case is having an effect....you can remove the battery and remove the Sensor sitting underneath the battery...aiming upwards.
Measure the resistance of this sensor at room temperature..should be about 2,000 Ohms. Heat the sensor over a lamp bulb and the resistance should drop down to about 200 Ohms.

This Battery Temp Sensor has its Black/Light Blue wire going to ground via a very long route.....I had the problem that somewhere along this long route the ground wire got broken so I spliced in a section of wire onto this Black/Light Blue wire and connected it straight to a clean chassis/engine point and problem was fixed.

 

[Tog]

I had battery issues after changing water pump. I put a new sepentine belt in snd although it was apparently the stock size it wad 15mm longer than the old one and not supplying enough resistance to turn the alternator properly.

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