[DeTomaso] Alternator problems still

[Will Demelo]

I’m replacing a GM alternator 1-wire with a new GM  1-wire alternator.
There are 2 tabs on the alternator. #1 tab (field) should be connected to the blue/blk wire (on original 4 pin regulator plug) that goes directly to the “gen” light on the dash. Apparently, this does not have to be connected for the alternator to work.
Tab #2 (sensing) should be connected to the yellow wire. This is battery voltage.
The alternator worked fine (albeit low voltage, it was steady) with only the yellow wire (sensing) connected or the yellow wire AND the blue/blk wire. All was fine until I revved the car to 4k rpm and it seemed the motor was breaking down on ignition. I turned the key off and the motor still ran. It didn’t die until I disconnected the blue/blk wire from the 4 pin harness.
Now, the alternator does not work with just the yellow (sensing ) wire connected. It needs thew blue/blk wire connected to work but runs on.
On another note, a friend told me that there should be NO electrical connection between the yellow and blue/blk wire. There is resistance between the 2 wires with the battery disconnected and the key switched on.
ANy help appreciated.
Will