Alternator, regulator wiring

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May 13, 2007
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Fort Collins, CO
I've been having some persistent electrical problems and could use some simple wiring validation. I have a new battery, starter, alternator, and voltage regulator. The new alternator has be bench tested and was putting out around 14.7 at peak. In the truck, I'm getting an even 12.3v which is constant at idle and under load. I can start and drive fine during the day, but it can't support headlights. I swapped out the external regulator thinking that may be the issue, and the one I got from coolcruisers has different hookups. I'd appreciate if someone could check the wiring here and make sure it is right. F goes the the one input on the regulator, E is grounded, N wasn't hooked up on the last one so I left it alone.
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I can't tell what the wiring is by just looking at the pictures and I don't know what you mean by swapping out the external regulator (for what?) and what hookup means. Different plugs or different circuits?

Wiring an alternator is pretty simple. The B+ lug goes to the amp meter - side (opposite the side that goes to the battery). The OEM wire is a large white one with a blue stripe.

The F wire from the regulator goes to the F terminal on the althernator. This is a white wire with green stripe.

It is good practice to run a ground wire from the alternator case to the voltage regulator case. This avouds problems with floating grounds screwing up the voltage regulation. The OEM one is white with black stripe.

You can quickly check if the alternator is putting out the power by momentarily jumping between the B+ lug and the F terminal of the alternator. The voltage shold jump up above 14V.

If you have a lot of high current after market accessories, the stock alternator may not be able to keep up with them even if everything is working OK.
 
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Thanks for the response. By swapping out the regulator, I meant the old one for a new one, which has some slight differnet hookups (new one only has F, old one also had E and one other). Either way, I've got B+ to the battery, F on the alt to F on the ext regulator, and a ground from the alt to the regulator case. I double checked the ground on the alternator with a battery charger and got a good spark. I'm going to take the alternator out and get it bench tested again, but I wanted to make sure the wiring was right first.
 
That wiring should work. Why take it out to test it? All you need to do is put 12 V on the F terminal of the alternator and it will make as much power as it is capable of. The system voltage should rise above 12V.

Did you check the engine fuse that powers the voltage regulator? What is the voltage on the F wire when it is both connected and disconnected with the key on?
 
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