Ford PCM controlled charging system

    I have a 2006 4.0L Explorer limited.  Charging problem is after 5-10min run time not drive time it stops charging.  Not just controlled charging but just battery voltage and zero amp output at alt.  At that point load test battery and zero amp at battery.   Light on dash and code P0620 and that’s it.   My system has at voltage regulator 3 wires.  One red one green and one yellow.  When it does charge all test are normal except yellow PCM wire duty cycle goes to 95-100%. When first start of the day test duty cycle starts normal koeo 0% warm engine 32% and all is well voltage and amperage.  I’m at the pulling the PCM trigger but wondering did I miss something.  All wires have good voltage drop and resistance test.  Battery good truck has 180k runs great we are in the rust belt so I need 4x4.  Also if I ground the screw on back of alternator at regulator it charges full voltage 15+. Diagram is my system

Are you losing the command from the PCM on the Yellow wire when the alternator stop charging?
You should get voltage on that wire after engine started.

It can be normal KOEO zero duty cycle then running it is normal 30% dudy cycle. After 5-10 min it goes to 100%.

Ok. I will let others chime in for the time being.