1996 Mustang GT Alternator not charging

RyanCooper

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This is starting to drive me insane, only thing left on this car is getting the alternator to charge before i can drive it... i wanna drive it!! anyway, has a new alternator, i've made sure all my grounds are connected (unless im just completely missing one or more... there's lots and this car was a roller so...), I've even messed with the gauge cluster (one i had looked fine, charging light turns on and works like it should, other cluster looked good too but still no change), and jumped the signal wire to a fused 12v source, to no avail. steadily drops from 11.5-12V and down as i let it run. any help would be GREATLY appreciated...
 

lwarrior1016

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How did you jump the signal wire?

Your alternator should have a yellow and green wire in the plug. Yellow should have constant 12v and green should get switched voltage.
 
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RyanCooper

RyanCooper

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How did you jump the signal wire?

Your alternator should have a yellow and green wire in the plug. Yellow should have constant 12v and green should get switched voltage.
I used a fuse tap, and tried a few different slots on circuits I knew were working, and ran it to both the wires (one was orange and white, other was green and red) since colors didn’t seem to coordinate with what I was reading. One made the battery light just come on, the other didn’t make any change, but went to the 3rd pin on the alternator connector. The yellow wire looks to just be the loop wire for the stator for me.

I get 12v at the green and red wire, and the big cable at the alternator.
 
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RyanCooper

RyanCooper

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I double checked my frame to motor mount ground strap, cleaned it, moved it to the other bolt on the motor mount from being shared with the main ground cable, still not charging.

Edit: i now see where the yellow wire comes in, it was my other connector i was confused about... swapped them, and jumped the signal wire to the alternator fuse with a fuse tap and now its charging just fine. i wish there was a way to have a self-exciting regulator for these lol
 
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lwarrior1016

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I double checked my frame to motor mount ground strap, cleaned it, moved it to the other bolt on the motor mount from being shared with the main ground cable, still not charging.

Edit: i now see where the yellow wire comes in, it was my other connector i was confused about... swapped them, and jumped the signal wire to the alternator fuse with a fuse tap and now its charging just fine. i wish there was a way to have a self-exciting regulator for these lol
So you’re missing 12v constant on the yellow wire?

When I’ve done a stand alone 3g alternator setup, the yellow wire looped back to the big positive post, and the green/red wire got 12v switched to excite the alternator.

Double check all of your fuses inside and out. There’s a reason that yellow wire isn’t getting voltage.
 

ttocs

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How old is the battery? Take an ohm meter and measure how much the resistance is between the battery and chassis and the battery and the block or alt. Should be as close to 0 as possible
 

ttocs

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Also did you check fuses? Don't bother with the manual it takes less time to pull and I spent them, don't forget the box under the hood
 

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