ALT Light
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From: Collierville
ALT Light
I have a 77 F100 with lights. Today when I was driving around the ALT light was flashing like a turn signal. It only happened when the engine was reved up but not at idle. I let the truck sit in a parking lot for about 20 min and when I started it back up the problem is gone.
What causes the flashing? I can replace the alt and voltage regulator if I need to but the flashing seems strange.
Also, I have been looking at alts on the internet and I was wondering if I can use a 70 amp instend of the 61 that the truck has if I replace it. It seems like the voltage regulator is the same and it should fit and the extra 9 amps might help.
What causes the flashing? I can replace the alt and voltage regulator if I need to but the flashing seems strange.
Also, I have been looking at alts on the internet and I was wondering if I can use a 70 amp instend of the 61 that the truck has if I replace it. It seems like the voltage regulator is the same and it should fit and the extra 9 amps might help.
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From: Virginia
Usually rpm related charging problems are worn brushes in the alternator. A rebuilt alt might be the fix.
You can install the larger alternator, just make sure it's the same diameter. Some of the larger alternators had larger windings, and thus were larger in size.
You can install the larger alternator, just make sure it's the same diameter. Some of the larger alternators had larger windings, and thus were larger in size.
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From: Collierville
Thanks for the quick reply. I guess I will be replacing the alt and voltage reg tommorow. Far as I can tell it is the original so I am sure the brushes are bad by now and it sure is cheeper to replace now than after a tow.
How do I verify which alt I have in now? Do I just measure the diameter. The 61 are listed at 5" and the 70 at 6" so I might not measure it right with it that close.
How do I verify which alt I have in now? Do I just measure the diameter. The 61 are listed at 5" and the 70 at 6" so I might not measure it right with it that close.
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codyingersoll123
1973 - 1979 F-100 & Larger F-Series Trucks
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Feb 2, 2009 10:30 PM
