Voltage Drop at 3,000 RPM - Ranger-Forums - The Ultimate Ford Ranger Resource


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Old 06-03-2008
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Voltage Drop at 3,000 RPM

Since this morning, it appears that when I get higher in the RPM range (above 2500 - 3000 RPM), my battery gauge drops like a rock. When it does, the needle moves erratically. However, when I come to a full idle, the gauge resumes working perfectly fine.

I don't see any signs of belt wear or hear anything. Anything I should check before replacing the alternator?
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Old 06-03-2008
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Well, it was definitely the alternator. Took it to Advance and got it tested... it was putting out about 23A @ 2000RPM.

Replaced the alternator and now the battery gauge is working just fine... drove her around the block to make sure.

Now I fear I've caused a new problem... it's idling at 500RPM vs the normal 1000RPM. I knocked one of the lines off of the round rubber ball thing on the passenger side while removing the old alternator. Put it back in... but she's idling rough. Starts up fine... but when I'm coming down in RPMs it goes right to 500 and stays there. Any ideas?
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Old 06-03-2008
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If you removed a cable from the battery when changing the alt , The PCM will take some time to relearn its settings . Just drive it.
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Old 06-03-2008
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Quote:
Originally Posted by OTRtech View Post
If you removed a cable from the battery when changing the alt , The PCM will take some time to relearn its settings . Just drive it.
Alright. Thanks for the tip!
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Old 06-03-2008
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Aye, drive it around some, get a pizza and some cold beverages and it will prolly be fine!
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Old 06-03-2008
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It was more then likely a vacuum line you knocked off. Get a new one, or see where it's broken and cut to length.
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Old 06-09-2008
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She's idling fine now. You guys were right... she just needed to learn how to idle again. You guys rock!
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