Car Batteries
Ford F-150

What would cause all the lights on a 2001 f-150 to flitter all the timealternator is fine and so is battery?

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April 26, 2008 3:52AM

Regulators are supposed to turn off and on quickly. When the alternator drops slightly below a threshold voltage, the regulator turns on, causing the alternator voltage to go up. When the alternator goes above a threshold voltage, the regulator turns off causing th voltage to go down. The idea is that the alternator keeps the voltage between two set-points. If the regulator operates too slowly you will notice the flickering. It doesn't mean that anything is wrong, it's just annoying. Sometimes you can run an alternator load test and the problem will solve itself, but usually you'll just need to live with it. *************************************************** I have the same truck and I had the same problem! Try this: check your fuses. I think that you'll find that the "Alternator field" fuse (under the hood--see your owner's manual) has an issue. In my case, the fuse looked good, but my voltmeter showed that I had a voltage on only one side of the fuse (you can test a fuse without removing it by contacting each side through a small opening in the plastic with the 'positive' contact and a ground point with the 'negative' contact; remember that the engine should be running for this test). If you have the same problem as I did, the flickering will eventually worsen until the fuse connection finally fails completely and it will appear as though your alternator has failed. Fortunately, I discovered the problem before it discovered my credit card.