How do I wire a one wire alternator?

Run one appropriately sized charge wire from the output stud on the back of the alternator to battery positive, or to the battery post on the starter solenoid.

Leave any factory plug unplugged. Tape it off so it cannot rub or short.

That is it. There is no exciter wire, no ignition trigger, and no harness to source.

The charge wire is too small. One wire alternators are more sensitive to wire size than an externally regulated unit. If there is too much voltage drop between the alternator and the battery, the internal regulator gets a false reading and the alternator will not charge. In many cases the OEM wiring is not sufficient. Use pure copper, not copper clad aluminum.

The case is not grounded. Paint and corrosion can stop the alternator grounding through the alternator housing, bracket and engine path. Run a separate ground wire of the same size as the positive so the alternator is properly grounded.

The pulley ratio is too low. A one wire unit switches itself on off shaft speed, so if it is not spinning fast enough it will not come on at idle. Bring the engine up off idle and see whether it starts charging.

The terminals are loose or over torqued. Recommended torque at the wiring terminals is 65 in-lbs, which is 5.4 ft-lbs. Do not over torque them.

Have it bench tested. If the wire size, ground and pulley ratio all check out, take the alternator to a local parts store and have it bench tested. Most of them do it at no charge. That is what separates a unit that has actually failed from an install that is holding it back, and it is the result we need before we can move on a replacement.