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Confused about alternator wiring

16K views 13 replies 5 participants last post by  445 FE Bronco  
#1 ·
1978 f150 with stock 400 motor. This is the 2nd new remanufactured alternator. 2nd new voltage regulator with in a couple months. Output is reading 17 volts at the battery.

Im looking to make a new wire harness but not quite sure its all connected correct. Im confused on which diagram to use. I dont have a voltage gauge inside the truck but there is a gauge that says "Alt" that doesn't seem to work. It just stays in the middle of "D" and "C". I dont even know what that gauge indicates. Which diagram should I be using to rewire this?

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Discussion starter · #3 ·
Thanks, out of curiosity what does the D and C mean on that gauge? I dont plan to use it if its problematic. unfortunately I just found out about that upgrade recently. That's going to be on my to do list to upgrade later but for now I would like to get my set up working properly.

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Discussion starter · #7 ·
Does my alternator need to be grounded? There is a stud on the alternator that says ground. Also, I was reading that I don't need the stator wire hooked up behind my alternator? It is currently connected behind the alternator.

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Discussion starter · #9 ·
Ok so my battery was completely dead this morning. I left everything wired up on my alternator the way it has always been. I checked to see what killed my battery and found that I get 3.5 amp draw with everything off. As soon as I unplug the regulator the draw goes away. Or when I unplug the "f" terminal behind the alternator the draw goes away. Bad alternator?

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Discussion starter · #11 ·
Just an update.. Picked up my third new regulator this time from autozone and seems to be working as it should now. Also, my ammeter is working which I don't know if that's a good thing or fire hazard now. But had to go through 3 regulators!

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Discussion starter · #13 ·
Yea I almost tossed everything in the trash and was ready to head to junk yard tomorrow for the 3g. I was passing by an autozone and decided to give it one last shot and worked. Im over this set up though. Next time I'm at the junk yard I will definitely be getting a 3g and parts for the upgrade. Its my only vehicle right now so I cant afford too much down time.

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