... Edited...
Plus i just learned why my alt has two wires
The GM SI series should have 4 wires...
The smaller (#1 Position) in the plug is the 'Excite' wire.
Gets things charging right away, keeps the alternator making power longer as the RPM goes down.
It's also a 'Ground' (through the rotor) when the alternator isn't charging,
But turns 'Positive' as the alternator starts to charge.
This means with a wire through your ignition switch (Switched Power) to this terminal,
Then ran through a light bulb on the dash, you can have an 'Idiot' light on any common SI alternator.
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The larger (#2 Position) in the plug is the 'Sense' or 'Line Sample' wire.
By getting rid of AMC's 'Short Cut' on installing,
You can move that 'Sample' source back someplace it will do some good,
Like AFTER the fuse block someplace,
And the alternator will start to produce enough to supply the fused accessories without the voltage dropping, your lights dimming, ect.
This wire can hook to full time power, it won't suck the battery dry.
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The big wire on the back, the 'BAT' terminal is the feed to the battery positive.
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The big wire IT SHOULD HAVE is a dedicated 'Ground Path' wire back to the battery Negative.
Another AMC screw up...
If you are going to give a direct path for POSITIVE, doesn't it make sense to give a direct path to Negative to get that circuit completed?
Nothing like trying to drive 40 amps of current through a 2 amp 'Ground' connection that is mostly rusted bolts, corrosion, painted metal, ect...
Then complaining about the lights not working, low volt gauge readings, ect.