Hey all so my alternator failed about a week ago and drained my battery. Tried charging the battery didn't hold a charge so I picked up and new battery and alternator. Installed yesterday night and the jeep started up but after about 45 minutes of driving the check gauges light came on and the voltage read below 9. Anybody have any ideas why? My jeep is a 98 i6 4.0
Thanks Eric

 

Also jeep died this morning so I jumped it, it ran for 2 minutes then sputtered out and died again.

 

how are your battery connections, and cables? Got a voltmeter?

 

Battery connections are good just re did them before this happened. Also tested it when it happened read 13.4

 

So is it going dead while driving or sitting overnight? 13.4 with the engine running, across the battery terminals?

 

It's going dead while running and it is 13.4 across battery posts

 

While running it should be 14-15 volts, when not running it should be about 12 volts at battery for both, It would seem to be something with the computer if all the wiring is clean and good I would assume.

 

Is there anyway to test if it is the computer?

 

Know anyone with a similar XJ to swap the computer out of and test?

 

I do actually will run the test tomorrow and see I hope it's something simple haha

 

So not computer, got new alternator tested only put out 8 volts. Put a new one in and the gage reads 12 volts battery voltmeter test reads 14.2. As soon as I put it in drive gage voltage drops to bottom and check gauges. In at a loss please help

 

Might seem like a no brainer to you, but I'm inexperienced with Jeeps and cars in general, so it took me a few hours of hopelessness and desperately ridiculous diagnostics, but it turned out that some of my fuses in the cabin under the drivers side were totally corroded and had completely fallen apart from long exposure to a small leak in the windshield. One of these failures prevented the alternator from charging the battery....I have the Renix system, and am not familiar with the newer models and their fuse setup, so I apologize if this post makes no sense... But its an honest suggestion anyways.
-Evan

 

I checked them before the second new alternator but I'll check em again. Thanks for the suggestion

 

This may sound strange but on one of my other XJ's I had the same problem and it turned out to be the starter. The battery would be fine if it sat over nite. But if I would run it for more then 20 or 30 minutes it would drain the battery. Just something you might want to have checked out. Hope you can find the problem.

 

I had a similar problem. I put subs in a few weeks ago and my battary just started to die when it would sit there. So i thought it was my subs drawing power. but my starter was having problems before. And it wouldnt even jump anymore so i put a new starter in it on saturday and nownit starts right up and my battery hasnt died since then. Hope this helps.