79 not charging, need help
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From: Springfield, OR
79 not charging, need help
I just bought a 79 f250 with a 460 and it will not charge. If I disconnect the battery it will die so I know the alternator is not charging. The alternator looks brand new. I think it is a wiring issue. I looked at autozone.com but the wiring diagram looks different than what I have. Any other sources for wiring diagrams? Any advice would help.
Thanks,
Scott
Thanks,
Scott
Fleet Owner
Joined: Aug 2005
Posts: 23,666
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From: Easton,Ks
Originally Posted by scottmoore
I just bought a 79 f250 with a 460 and it will not charge. If I disconnect the battery it will die so I know the alternator is not charging. The alternator looks brand new. I think it is a wiring issue. I looked at autozone.com but the wiring diagram looks different than what I have. Any other sources for wiring diagrams? Any advice would help.
Thanks,
Scott
Thanks,
Scott
1977:
http://i54.photobucket.com/albums/g9...itionDP277.gif
1982:
http://i54.photobucket.com/albums/g9...itionDP282.gif
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From: Virginia
Here's a diagram too.
1st thing to do is take a meter and see if you have 12 volts on the bat terminal of the alternator with the truck off. If you don't, then you may have a fusible link bad in the output wire of the alternator.
If that's good, then take the "f" wire off the alternator and hook a piece of scrap wire to the "f" terminal that will reach the battery +. Get the engine started, and while watching the voltage on the battery with a meter, touch the "f" terminal wire to the battery +. This will throw the alternator into wide open charge, and you should see the meter voltage jump up and the alternator may start whining. If this works, then you know the alternator is good.
Write back in if you make it this far.
1st thing to do is take a meter and see if you have 12 volts on the bat terminal of the alternator with the truck off. If you don't, then you may have a fusible link bad in the output wire of the alternator.
If that's good, then take the "f" wire off the alternator and hook a piece of scrap wire to the "f" terminal that will reach the battery +. Get the engine started, and while watching the voltage on the battery with a meter, touch the "f" terminal wire to the battery +. This will throw the alternator into wide open charge, and you should see the meter voltage jump up and the alternator may start whining. If this works, then you know the alternator is good.
Write back in if you make it this far.
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Joined: Dec 2006
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From: Springfield, OR
Originally Posted by Franklin2
1st thing to do is take a meter and see if you have 12 volts on the bat terminal of the alternator with the truck off. If you don't, then you may have a fusible link bad in the output wire of the alternator.
If that's good, then take the "f" wire off the alternator and hook a piece of scrap wire to the "f" terminal that will reach the battery +. Get the engine started, and while watching the voltage on the battery with a meter, touch the "f" terminal wire to the battery +. This will throw the alternator into wide open charge, and you should see the meter voltage jump up and the alternator may start whining. If this works, then you know the alternator is good.
Write back in if you make it this far.
If that's good, then take the "f" wire off the alternator and hook a piece of scrap wire to the "f" terminal that will reach the battery +. Get the engine started, and while watching the voltage on the battery with a meter, touch the "f" terminal wire to the battery +. This will throw the alternator into wide open charge, and you should see the meter voltage jump up and the alternator may start whining. If this works, then you know the alternator is good.
Write back in if you make it this far.
1st test was good. I have 12.4 volts between the two.
2nd test passed. The alternator is good. When I touched the + with the wire from the "f" terminal the volts started climbing from 12.4 to 13.8. It would have gotten higher but I stopped since it showed me my alt. was good.
Next, with the key on I was getting 12.4 volts from the yellow and the green/red wire that was going to the voltage regulator. I am guessing that the new regulator that is on there is bad. Am I right? Are there other test I should do before I go buy a new one?
Thanks for the help,
Scott
Fleet Owner
Joined: Aug 2005
Posts: 23,666
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From: Easton,Ks
Make sure the regulator is grounded, sometimes where it is screwed on to the body it looses ground and stops charging. Also make sure there is a ground from the regulator to the alternator.
A lot of regulators get changed out for no ground and when the replacement is screwed on it gets a ground and then you say you had a bad regulator.
A lot of regulators get changed out for no ground and when the replacement is screwed on it gets a ground and then you say you had a bad regulator.
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From: Springfield, OR
I checked the regulator and it was grounded. Decided to buy another regulator and now it is charging. Guess the new reg that was on there was bad.
Thanks for all the help guys.
Scott
Thanks for all the help guys.
Scott
