2004 JGC 4.0 6 cylinder batt/alternator prob - JeepForum.com
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Unread 08-19-2014, 01:18 PM   #1
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Join Date: Aug 2014
Location: Boston, Ma
Posts: 7
2004 JGC 4.0 6 cylinder batt/alternator prob

Daughters 2004 JGC 6 cylinder has been having starting problems on 2 occasions lately. Has the dead/low battery symptom click click. It will start with a jump and run fine and will start fine until the next episode.
Last week she was out cleaning the car had the radio on for 30 min and car would not start had to jump. Has been starting fine until this morning and had to jump again. Got it started she went to school came home starting ok.

I got my digital fluke meter and tested the battery about 12.5 volts
Tested the battery with car running and get 13.35v
Also checked from the post on the alternator and battery + side and got the same 13.35v
Had her put on all ac, lights high beams, high fan and it dropped to 13.23v.

We bought the car 3yrs ago used and the battery in car is only 2 yrs old.

What would you do start with a new battery or does the alternator seem to not putting out enough volts dc.

I checked my dodge ram 1500 4.7 eng and the alternator is putting out 14.5 volts about 1 volt higher.

I'm going to take to a battery place thats all they do is batteries. They will do a load test and check alternator to see whats up.

Cost for battery is $95.00 and tax. They will check and install for that price.

I can do the install but cant do a load test on the battery so hope the reply back tomorrow with results.

I would only like to buy either an alternator or a battery no both I hope.

One more question would the 1 volt difference make a difference in the problem?


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Unread 08-19-2014, 01:21 PM   #2
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Join Date: Aug 2014
Location: Boston, Ma
Posts: 7
Well replaced the alternator with a used one. The output is 13.97 and had her put everything on and seemed to stay at the 13.90 out.
The used alternator from what I can see/measure is about .5v more out. I hope this will help if not nothing lost for $20.00 for used.
If this don't work has to be the battery.

I cleaned the terminals with baking soda and water.

One thing I noticed on the battery is this is the third time I cleaned the terminals they seem to corrode with acid on both sides quite fast. Also the positive side always seem to be wet asid not the dry acid crystals that form.

What would cause the positive side to be wet and crystallized acid on terminal?

Any advice/opinions if the original alternator was borderline and if the used one might do the job? I guess time will tell
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