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Old Jan 12, 2007 | 03:54 PM
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77 wiring problem

I've got a 77 F250 that keeps eating alternators and Vregs. It blows the fusable link (which is now a 60 amp maxi fuse) as well. The strange thing is that it happened, I repaired everything and them it happened again about three months later. I haven't found any shorts and haven't found anything that would pull enough current to take out the fuse. I am thinking along the lines of something unfused is intermittently shorting. Any ideas?
 
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Old Jan 12, 2007 | 04:03 PM
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From: Easton,Ks
The "A" wire does not have good conductivity back to the battery.
 
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Old Jan 16, 2007 | 10:01 AM
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Thanks for the info, Bill. So does that mean if the battery terminal is corroded it will take everything out, or will it just take out the fusible link? You would think that they would design it to be a cheap fix. I replaced the Maxifuse (fusible link) and measured current from battery ground to the ground cable and have no drain. I think this indicates that the Vreg and Alt are OK. I will fire it up this weekend and see what I have. Thanks again for the help.
 
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Old Jan 16, 2007 | 05:44 PM
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Maybe something to do with the AMMETER wiring or fuse box corrosion ?
 
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Old Jan 17, 2007 | 12:12 PM
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From: Easton,Ks
Originally Posted by Pocca
Thanks for the info, Bill. So does that mean if the battery terminal is corroded it will take everything out, or will it just take out the fusible link? You would think that they would design it to be a cheap fix. I replaced the Maxifuse (fusible link) and measured current from battery ground to the ground cable and have no drain. I think this indicates that the Vreg and Alt are OK. I will fire it up this weekend and see what I have. Thanks again for the help.
It means if the "A" terminal at the voltage regulator does not know what the Battery Voltage is it can not regulate the voltage the A/C Generator puts out and the voltage can go quite high. This "A" wire must have good conductivity back to the battery so it has the same voltage on it as the Battery does.
 

Last edited by subford; Jan 17, 2007 at 12:17 PM.
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