Wiring Diagram 97 Ford F150 Alternator
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No charge
- kemperhills
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No charge
My son drives a 1997 F-150 with a 4.6L engine.
It stopped charging and we took the alternator off, took it to a parts house and they said the alternator was bad. Bought a rebuilt one and installed. The truck still doesn't charge.
Took the alternator off of my F-150 installed it on his and it still won't charge.
I have checked the maxi fuse, the mini fuse and both are ok. I checked the battery voltage at the B+ post on the alternator and there is 12V there. I checked for 12V at the alternator for the exciter voltage and it is there. I have checked every fuse in the truck, both under the dash and in the power distribution box under the hood and all are ok. I have checked the continuity of all the wires involved and all a good.
So what could be causing this truck not to charge. Thanks.
- 3FOX
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Re: No charge
Post by 3FOX »
Is the charge light on?
If no, either the inline fuse is open (#19), lamp is open or the ignition switch is not passing power to this circuit and to the regulator.
If yes, the circuit is complete and getting it's ground from the regulator. As the no charge indication.
All there is left is the 20a mini inline fuse powering the field winding and the mega fuse and cables.
Otherwise there might be a harness plug up issue at the alternator. Look closely at the plug contacts and leads.
Your just missing it some place.
I would assume the alternator is not the fault, at this point..
To see this wiring look into a Haynes book page 12-17.
Good luck.
- kemperhills
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Re: No charge
Post by kemperhills »
3FOX wrote:Is the charge light on?
If no, either the inline fuse is open (#19), lamp is open or the ignition switch is not passing power to this circuit and to the regulator.
If yes, the circuit is complete and getting it's ground from the regulator. As the no charge indication.
All there is left is the 20a mini inline fuse powering the field winding and the mega fuse and cables.
Otherwise there might be a harness plug up issue at the alternator. Look closely at the plug contacts and leads.
Your just missing it some place.
I would assume the alternator is not the fault, at this point..
To see this wiring look into a Haynes book page 12-17.
Good luck.
Well, this truck has a gauge, but same thing. And I have checked every cable with connection, fuse more that once. I even checked the output of the alternator at the B+ post on the alternator and just battery voltage. The 174 amp maxi fuse and the 20 amp mini fuse are both good as is the continuity in all wire involved in the charging circuit. I just don't know. It has the 12v exciter voltage. But one thing I haven't mentioned before is that the gauge will move from 8V, which is the lowest value shown to about 10v when the truck is started. That is, the gauge will move some, but only a little.
- 3FOX
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Re: No charge
Post by 3FOX »
If the battery cranks the motor ok, that part of the system should be ok for battery condition and cables/connections.
All you have left is the wiring, fuses and alternator.
Might be a fuse holder rather than a fuse.
Good luck.
- kemperhills
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Re: No charge
Post by kemperhills »
3FOX wrote:If the battery cranks the motor ok, that part of the system should be ok for battery condition and cables/connections.
All you have left is the wiring, fuses and alternator.
Might be a fuse holder rather than a fuse.
Good luck.
Thanks guys for the replies. More info since I posted. We took the alternator of and returned it to the parts house and they checked it and said the alternator is good. Returned home and took the alternator off of my F-150, put it on my son's truck and it won't charge. Put the rebuilt alternator on me truck and it charges. Just today, Sunday, checked every thing again and even ran a jumper from the positive battery post to the exciter wire going into the alternator and it still won't charge. I have been a mechanic for 45 years and I have never seen this kind of problem before that I can remember. Just don't know. Thanks guys.
- projectsho89
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Re: No charge
Post by projectsho89 »
kemperhills wrote:Problem solved, thanks guys for you help.
..and what was the problem?
2001 F250 SD V10 4X4 - Just arrived Feb 2011
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- 3FOX
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Re: No charge
Post by 3FOX »
Come on kemper, admit it. 
Good you got it.
- Navy92586
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Re: No charge
Post by Navy92586 »
Kemper
So what fixed your truck because I have the exact same thing going on. And I am out of options.
Source: https://www.fordf150.net/forums/viewtopic.php?t=114136
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