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Old Aug 2, 2009 | 05:48 PM
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No Charging

The UVC harness came loose on the driver's side and I ended up running on only the passenger side for a bit until I could get back to the house and fix it. As soon as that was fixed, the battery light on the dash was lit constantly. The batteries are less than a week old, and the alternator tested just tested good today, however it is not charging when on the truck. There is 12 volts from the post on the alternator to ground when running. I've also ohmed from the post on the alternator to both battery positive terminals.

I'm thinking that I had to mess something up when I pulled the valve cover to plug in the UVC harness, but I"m not sure where to start...Any help is appreciated
 
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Old Aug 2, 2009 | 05:54 PM
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What voltage are you reading when it is running? Might just be a bad alternator. Also check the connector at the alternator to make sure it did not get damaged while working on the truck.
 
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Old Aug 2, 2009 | 06:00 PM
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12 volts when running. Alternator is good. I'm pretty sure connectors on alternator are good. Is there another way to test them?
 
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Old Aug 2, 2009 | 06:12 PM
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The auto parts stores can't test the full functionality of the alternator. Maybe you have a buddy with a same truck that you could test in yours. I think the 6.0 alternators will work as well.
 
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Old Aug 2, 2009 | 06:17 PM
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You should see more than 12v from the alternator when running. High 13's or low 14's is what you should be seeing. Try turning on the headlights, hazards, radio, & AC and see what your reading from the alternator is. If it doesn't go above 12 volts, you need a new one.

The auto stores don't always identify a bad alternator. I've had one that bench tested good (supposedly) but a new alternator fixed the low voltage issue.
 
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Old Aug 2, 2009 | 06:36 PM
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Voltage goes down a bit to 11.75 with everything on and engine running. I may just have to bite the bullet on a new alternator and hope it fixes the problem. This one is a few years old.

What are the two green wires that plug into the alternator for?
 
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Old Aug 8, 2009 | 08:45 PM
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Fixed It! It was the alternator. I installed a new 200 amp unit from DB electric and their wire kit from the alternator to the battery. After the install, the battery light was off, but there was still no charging. After checking everything again, I checked all of the fuses again, and found a 5-amp that was blown in the engine compartment. Replaced that, and there was charging. The next day, one of the brand new wal-mart batteries began spewing acid everywhere. Replaced that, and now everything seems to be 100%. Ready for Winter!!
 
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Old Aug 8, 2009 | 10:27 PM
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Good fix and thanks for getting back to us. Can you tell us which fuse you replaced? Keep the old alt as a spare. It may be good and the blown fuse may have been the real problem.
 
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Old Aug 8, 2009 | 10:46 PM
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Originally Posted by PaysonPSD
Good fix and thanks for getting back to us. Can you tell us which fuse you replaced? Keep the old alt as a spare. It may be good and the blown fuse may have been the real problem.
Yes, thanks for getting back to us. Reps sent!
 
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Old Aug 8, 2009 | 11:27 PM
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yea what fuse... mine started this about 2 hr ago. batt light was on its reading 12v at both batts and 11.6 when at idle and all lights on. batteries are like 5yr old and alternator is 10 ha ha im hoping it may be this fuse.... guess your problem moved to my truck ha ha
 
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Old Aug 9, 2009 | 12:19 AM
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Originally Posted by bigsteve1969
yea what fuse...
My guess is that it was a voltae regulator "A" field fuse. The fuse chart doesn't make a lot of sense but it could have been under hood fuse #5, 6 or 7. Check those.
 
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Old Aug 9, 2009 | 12:56 AM
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Yes, our fields are fused, and a blown one would render an alternator temporarily inoperative.

Pop
 
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Old Aug 9, 2009 | 02:08 AM
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When my 97 Explorer quit charging a quick look at the charge circuit wiring diagram told me which fuses to check.

BINGO, mini fuse 6 labeled "generator/voltage regulator" in the power dist box was blown. Replaced it & problem solved.
 
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Old Aug 9, 2009 | 09:06 AM
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alright i'll do some checking around
 
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Old Aug 9, 2009 | 09:22 AM
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Originally Posted by bigcountry560
Fixed It! It was the alternator. I installed a new 200 amp unit from DB electric and their wire kit from the alternator to the battery. After the install, the battery light was off, but there was still no charging. After checking everything again, I checked all of the fuses again, and found a 5-amp that was blown in the engine compartment. Replaced that, and there was charging. The next day, one of the brand new wal-mart batteries began spewing acid everywhere. Replaced that, and now everything seems to be 100%. Ready for Winter!!
The common cause of this is overcharging.
I recommend checking the voltage on that new alternator.
 
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