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Charging system malfunction.

694 views 11 replies 6 participants last post by  bluejunior 
#1 ·
I am getting basically zero electrical power with a new alternator, battery and I replaced the belt cause it needed to be done anyway. I have checked as many fuses as I could think of. This sums it up, read on for more info if needed.

My 98XJ 4.0 has been having some major electrical issues. About a week ago I went to start it up and it barely started, when it did the voltage read almost nothing. I let it sit for a few minutes and things didn't get much better. I turned it off and checked my battery voltage and it was low. Figured it could be the alternator. After checking some fuses and testing the battery again with the engine running and still low voltage, I deducted it was in fact the alternator. Ran and grabbed one swapped it out no problem. Started it up and it was sluggish at first, but I figure the battery just needed to charge up. 5 minutes down the road, complete loss of power and would not restart. Called AAA and got a tow back home. Bought a new battery to see if that would help. It did not.

What could be causing this? I checked just about every fuse I figured could relate to this happening, what am I missing or what is something I should be checking that I'm not thinking of? Thanks for any help/suggestions.
 
#3 ·
I will have to check that wire, did not think of it. The volt meter was quality and I did take readings, however it being a little over a week ago I cannot remember what they were. I want to say they were around 6-9v with the engine off, with the engine on around 9-11v.
 
#4 ·
Where did you buy the alternator ?


Just because it was "rebuilt" does not mean it works correctly. "Lifetime Warranty" parts have a high failure rate, and often have a shorter service life than the original Jeep parts.
 
#5 ·
Got this one from NAPA. That is something that crossed my mind, maybe it was bad rebuild, but I didn't think the odds of that would be very high. I haven't had as much time to work on the issue as I would like, but I have thought of pulling it out and bringing it to get tested. At this point that may be my easiest and cheapest option before I get to deep. Any suggestion or input as to what major auto stores have the best reputation with rebuilt parts like this? Any to stay away from? Thanks for the input here.
 
#6 ·
I do not buy any "Lifetime Warranty" parts. You end spending the rest of your lifetime exchanging them for another piece of junk. I did buy the cheapest NAPA alternator, and did have it fail after a few months. Exchanged it for the premium NAPA alternator, and it was OK.
 
#7 ·
Good advice. I will get this one tested and see how that goes. If its junk I will just buy a new quality one instead.
 
#9 ·
PCM failure is very highly unlikely. Alternators fail all the time, and are the more logical place to start diagnostics.
 
#12 ·
For no charging, test the alt, and if it tests good, take it to another store and test it again on a different machine. If it still passes I would check continuity at the fuseable link (from the power distribution to the batt) The ground (from the batt to the body) and the WIRES going to the PCM. PCM failures are EXTREMELY rare, but a failure in one of the wires in that pigtail is definitely possible.

In my case I did all of the above, had the alternator tested 7 times at four different stores (all passed) and it still turned out to be the alt.
 
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