Dash panel battery light

[1875]

Hello. New to the site with one quick question.

2002 liberty 194000 miles, 3.7 6 cylinder. With a Consistant issue. Start engine and battery light will be off at which point my voltage meter will see 14.1 volts coming from alternator . Drive for a few blocks or miles and batt light will come on. With my meter i will then see 12.1 volts at the same test points. Shut engine off and immediately start back up and same sequence of event will happen. Alt possibly produces a slight noise. Did not do the old screw driver test but my guess is that component is the noise maker.

Alt is original .replace it ?

Thanks 1875.

 

[03GoingStrong]

O'Reilly. Pep Boys and possibly others can test the alternator (on or off the vehicle). Call your local parts house and see if they do. Make sure the "slight noise" isn't a belt slipping or something. Take a look at condition of wiring associated with the alternator and battery.

 

[DadOSix]

Just thinking out loud -

if the alternator originally shows as charging, but then drops out,
Could this be a faulty battery temp sensor? Hot battery - stop charging?

 

[LibertyTC]

Welcome to the forum.
194K miles that alt has lasted well !
Are your battery terminals tight, clean & free of corrosion ?
Alt noise & 14.1 volts then battery warning light comes on at 12.1 volts (that is low) = time for a new Alt.
It is a good Idea to have Alt tested and a load test on battery wouldn't hurt either.
See this thread as well : https://www.jeepkj.com/threads/replace-alternator-or-repair-it-kj.76170/

 

[Billwill]

The early KJs like the 2002 definitely have a Battery Temp Sensor under the battery....this was dropped in the later KJs although the manuals still refer to it.

If this fails it definitely sets off the battery light so if your alternator is charging the battery OK then it may be this Temp Sensor.

Remove the battery and you will see the sensor facing up at you.

You can remove it and place an Ohm meter across it to measure its resistance at room temperature.
Then heat it up by means of a hairdryer or place it on an incandesant lamp...resistance should change as it heats up.

I had this problem on my 2002 Export CRD....Battery Lamp came on solid although the alternator appeared to be charging the battery OK.

Had the Alternator tested and it checked out fine.

The one side of this Sensor is supposed to go to ground somewhere via a Splice inside a large loom....this ground was missing on the one side of the Sensor so I cut that wire off and grounded it direct to chassis...no more problems for the last 10 years!

Your problem sounds to me more like a bad alternator or bad connections and the battery grounding to engine and chassis may be bad.

Download the 2002 Jeep KJ Manuals here...section 8W has the wiring diagrams.

www.colorado4wheel.com/manuals/Jeep/KJ/