running a painless kit and a Denso alt. Directions for the Painless have an "exciter" wire from the alt, Denso says ONE wire.. opinions.. Also is the plug on the back of the Denso for your volt gauge?

If your alternator builder said it is a 1 wire it does not need the "excite" wire.

I would tap the ignition circuit for your volt meter.

A 1 wire alternator does not use a "reference" wire for the internal regulator.

Denso makes a lot of different Alternators

If it's a one wire alternator adding the wire like you are being told can make the engine keep running when the ignition is tuned off.

Seen it happen many times. It will back feed through the wire and keep the ignition on.

As stated an actual one wire alternator should be one wire. However if you are doing the Toyota Denso alternator swap I can attest that it will not charge without both the exciter and sense wires hooked up.

Thanks, I'll have to look up the part number. What do you guys do with all the extra wires? This harness has a bunch. Thinking about just leaving them neatly in the harness tucked away just incase the next owner wants to use a standard MP ignition system instead of MSD and Denso.