voltage regulator
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Based on your most recent description, I agree that it sounds like your truck is set up for idiot lights, and the PO hacked the wiring near the voltage regulator. My advice is to restore the wiring near the voltage regulator according to my first post, which is the correct configuration for idiot lights. This will set up the voltage regulator to match the idiot light setup dictated by your cluster.
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
This is the wiring harness from the alternator to the solenoid and voltage regulator.
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Senior User
Joined: Apr 2014
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Ok thanks fmc400 I will rewire it the way you said to using 16 gauge wire. The hot wire for the alternator you said should be a bigger gauge. Is 10 gauge good for that or should I go with 6 gauge? Ground for alternator I can use 10 gauge right? Should I also add a ground from a voltage regulator mounting bolt to the block ground? Should the alternator ground go to engine block ground or is the frame a good place for ground?
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Ok I will check them out and see the price. If its to much money I do have tons of wiring from gauge 6 to 16 if you know the oem gauge for the alt harness.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
The alternator itself does not need a separate ground wire. It grounds by bolting directly to the engine block. You cannot achieve any better ground than that.
Technically, simply bolting the regulator to the inner fender should be a good enough ground for that. However, most alternators have a small case-mounted stud labeled GND. This can be connected to one of the regulator mounting bolts. This helps isolate load-dependent return current from the sense loop and gives a little better regulation. Many factory harnesses came with this. 16 AWG is more than enough for that.
If you have a stock setup without several aftermarket electrical loads, I think 10 AWG should be fine for the heavy alternator-to-solenoid lead assuming the battery and alternator are in the factory locations, not too far apart from one another. In that case, use a 14-AWG fusible link at the solenoid. Most parts stores sell these with the ring terminal already attached and molded.
Heavier gauge certainly doesn't hurt, but after 10 AWG you are too big for the standard type crimp terminals.
Technically, simply bolting the regulator to the inner fender should be a good enough ground for that. However, most alternators have a small case-mounted stud labeled GND. This can be connected to one of the regulator mounting bolts. This helps isolate load-dependent return current from the sense loop and gives a little better regulation. Many factory harnesses came with this. 16 AWG is more than enough for that.
If you have a stock setup without several aftermarket electrical loads, I think 10 AWG should be fine for the heavy alternator-to-solenoid lead assuming the battery and alternator are in the factory locations, not too far apart from one another. In that case, use a 14-AWG fusible link at the solenoid. Most parts stores sell these with the ring terminal already attached and molded.
Heavier gauge certainly doesn't hurt, but after 10 AWG you are too big for the standard type crimp terminals.
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
The stock alternator harness has a ground built into it that grounds the regulator to the alternator. On the stock set up, you can't see it because it's wrapped with tape, four wires go into the rubber strain relief but only three wires come out. The strain relief has a metal tab that is used to bolt it to the stud on the alternator case. This metal tab is the ground terminal.
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Senior User
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The stock alternator harness has a ground built into it that grounds the regulator to the alternator. On the stock set up, you can't see it because it's wrapped with tape, four wires go into the rubber strain relief but only three wires come out. The strain relief has a metal tab that is used to bolt it to the stud on the alternator case. This metal tab is the ground terminal.
Thanks fmc I added a temporary ground 10gauge from regulator to the alternator ground until the new harness comes. I will update this thread when it arrives just incase the alt light doesnt work. Even though it should with new harness.
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MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
I guess I'm confused. I thought you were building an alternator-to-regulator harness by hand, hence your questions. What is a harness being ordered for?
As I said in my previous post, 16 AWG is more than enough for the alternator-to-regulator ground. It carries hardly any current at all because the inner fender is already grounded. 10 AWG certainly works but it's a waste. The only 10-AWG wiring necessary here is the alternator output feed, coupled with a 14-AWG fusible link. If you've already got it set up, then leave it, I just don't understand the immediate deviation from my suggestion.
As I said in my previous post, 16 AWG is more than enough for the alternator-to-regulator ground. It carries hardly any current at all because the inner fender is already grounded. 10 AWG certainly works but it's a waste. The only 10-AWG wiring necessary here is the alternator output feed, coupled with a 14-AWG fusible link. If you've already got it set up, then leave it, I just don't understand the immediate deviation from my suggestion.
Hotshot
Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
This is the one I ordered. It's for a '73 so it's a little different than the one you'll get.
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Senior User
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I just noticed the local autozone has different Alternators some with alternator connector and some without. It would be faster for me to swap alternators as mine is under warranty. Would it be better to swap alternators to one without an alternator connector and use the new harness I just got? Everything seems like it would work then.
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No my alternator does not look like the picture in post #22, mine has a connector. Local auto zone has an alternator that matches yours in post #22. Do I need to pick one up? Also what does the fusable link go to on the voltage regulator connector? My new harness doesnt even look like the picture in post #22 mine has 4 wires coming out, 2 wires go into a black boot. 1 orange wire goes into an orange boot and a black with red stripe bigger gauge wire goes into a red boot.