Alternator Problem F150
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Joined: Mar 2002
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From: Modesto USA
Alternator Problem F150
I have a '99 F150 Used for commuting and Fire Chief duties. 81,000
miles and running strong. The last month the alternator sheds at 3000 RPM? Checks fine 14.3 volts and rated amps. up to 3k and then shuts off and voltage goes down to battery volts? I don't run over
3k normally but do when going code 3. The voltage comes back up when I shift so it makes the siren sound real sick? All wiring has been checked. Any ideas?
miles and running strong. The last month the alternator sheds at 3000 RPM? Checks fine 14.3 volts and rated amps. up to 3k and then shuts off and voltage goes down to battery volts? I don't run over
3k normally but do when going code 3. The voltage comes back up when I shift so it makes the siren sound real sick? All wiring has been checked. Any ideas?
Freshman User
Joined: Aug 2001
Posts: 25
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From: Prattville
Alternator Problem F150
If you still have the original alternator with those miles on it I think it may be worn brushes. When they get worn way down the springs cannot keep them against the commutator at higher RPMs. Can't think of anything else that would do that. Brushes usually last 100K miles, but dirt roads and or high current loads (like lights and sirens) will shorten the life span. Hope that helps.
Rick
Rick
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