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Old 12-30-2018, 03:36 PM   #8
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Join Date: Jan 2005
Location: Kalamazoo, Michigan
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Re: another alternator thread...

Originally Posted by ymi5150? View Post
more info.

the alternator tested bad at a big box store. replaced it, same outcome so i'm not sure if i have another bad one (doubt it).

i jerry rigged a jumper from the hot post of the alternator to the field terminal and it fixed the issue. the truck idles at 12.6 and revs up to about 13.1vdc.

i dont like the current fix but it tells me that the 9 vdc wasnt enough to excite the windings. i would think the battery would run down over time since its not switched power.

thoughts? is there an internally regulated, self exciting alternator i could upgrade to?

Since you seem to know what wires do what, here's how easy it is to upgrade, this is not a self exciting alternator and you will need to have 12 volts on the exciter wire.

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If you decide to keep the external regulator, you can trace the brown wire on the regulator ( it's the exciter wire from the key switch) back to the firewall and check it for 12 volts with the key on.

Here is the circuit for the exciter wire from the key switch to the regulator.

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when I started my truck for the new cam break-in, I wired a key on hot source through a light and directly to the IR alternator I converted to,and it charged at 14.5 and the light went out as I described above.
It's basically what you did in your OP except that you need a resistance in the exciter wire (the light) or the engine may run on after key off. You also bypassed the external regulator so you can't leave it like that. If you ran the key on 12 volt wire with a light in it like I did, to the brown wire connection on the external regulator and you got the 13,5 volts at the alternator and at the battery then your regulator is working but it should be charging at 14.5 at 2K RPMs.

If you decide to get a three wire internally regulated alternator then here is a good way to wire it up. It eliminates the EVR altogether and you can use the brown wire from the firewall to the regulator,(provided you have 12 volts on it with the key on) and the red wire from the regulator and the main junction. Then you can eliminate the small blue and white wires to the old alternator.

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