pop those plastic covers off the fuse links and make sure all is nice and tidy there as well.

The narrower range would be a sign of a belt slipping less.  The thing about the ammeter is that it shows whether the battery or the alternator is supplying the current so can have a large swing as it goes negative or positive.  A voltmeter will always sit around 12.6 and the same current direction change will only cause a fraction of a volt movement on the meter.  Plus any "wild" movement of a gauge is a sign that the needle damping mechanism is damaged.

You can buy spray-on belt dressing for a few dollars.  But any squeaking of the belt is bad.  Once they start slipping the surface overheats and the rubber hardens.  Then they slip more.

New belt, no slipping, gauge still fluctuates. The brake light in the gauge cluster is dimming and brightening as well. Measured alternator output at the source and it is varying between 13V and 16V at idle increasing to about 18V to 15V with increased revs. Internal regulator problem I'm thinking.

If you can, stick your meter probes through the back of the T plug, or pull the T plug partially off, and measure voltage at the S pin (can't remember if it's the vertical or the horizontal of the T).  Dave's adapter works on the assumption that the wires from the external VR are correct.  Sounds like you're missing the S connection.  S should connect to the battery positive circuit.

If you don't know which is S, measure both with the key at Run.  They should both show battery voltage then.

Just heard from Dave, looks like a faulty alternator. Should never be more than 15V off idle , the range should be smaller as well. Off to Napa later for a new alternator!

Let's hope it's that simple. Wouldn't be the first time someone had to go back for another rebuild.

Not quite that simple, no ZX alternator available IN CANADA! At least no new or reman one. Searching for a rebuilder here in Edmonton.

Are you looking at cross-references too?  The early 80's Maxima alternators will work too.

Bad S same symptoms...

No I didn't know that a Maxima Alt is the same, will check onthat!

Thanks

Could be bad DOA alternator too.  They are pretty bad these days.  Made in China usually.  No quality control.

I'm still using an old 1981 Nissan alternator that I got from a junkyard engine I bought.  Probably 40,000 miles on it.  I have a new Autolite replacement from OReilly in the box on the shelf that I'll probably never use.  It's the lifetime warranty replacement for the first OReilly alt that crapped out soon after I installed it.  I'd go get a junk yard Nissan alternator myself.  Just make sure it's Nissan.

Just ordered one from Rock Auto, says it's a reman Hitachi unit. $79 CAD to my door!  Can't beat that! As an interesting side note, I drove the Zed to work today and the Amp gauge was steady as a rock! Slight dip into - side when TS on. So....intermittent problem? The readings I got with the multi meter definitely show a problem so I will replace it and see what happens!