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Old 04-14-2012
biketheozarks's Avatar
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Join Date: Nov 2011
Location: Northwest Arkansas
Posts: 205
4.0L electrical problems

Ok, my problem has been going on for going on several weeks now. When I rev my engine above 2500 rpm, the battery light begins to flicker. I thought maybe the serpentine belt was slipping at higher rpm, causing the battery light. My truck has died on me. So far I have installed a new serpentine belt, a new belt tensioner, and a new battery. I had the original alternator rebuilt. The guys who rebuilt it installed a new voltage regulator, 2 bearings, and a brush holder. The truck is doing better, and hasn't died on me again, yet. I am still getting a battery light above 2500 rpm. If it's at night time, the headlights do dim when the battery light is coming on. The connections to the alternator and the battery are fine, as far as I can tell. My Ranger is my only driveable vehicle, without it I can't get to work. Any ideas? The truck currently has 65,000 miles, and is in excellent condition. Thanks in advance for any advice!
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Old 04-15-2012
Rev's Avatar
Rev Rev is offline
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Join Date: May 2005
Location: San Diego, CA
Posts: 1,179
It sounds like your alternator is still not working properly. If you're handy with a voltmeter you can do some basic test to help identify potential problems with the charging system. Click Link

Note, after running the first set of base line tests, you can repeat with the RPM at the speeds that coincide with the symptoms your having.
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Old 04-16-2012
Blhde's Avatar
Join Date: Oct 2005
Location: Northern IL
Posts: 2,804
The connectors at the alternator can become brittle and can cause a bad connection.

Check to see if they are brittle.

Also clean your battery terminals.

To me it sounds like the diodes were shot in the alternator and they weren't replaced.
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