Well that did not work.
Cleaned PCM feet and fender reattached PCM and also added additional grounding wire. Revised ground battery wire to fender well after Dremel cleaning surface. ( I am concerned about this ground terminal. It is a loop lug with a saw tooth ID. It seems like not enought surface area to contact fender adquately). Cleaned and reattached battery wire to engine block and cleaned another wire on seperate lug next to battery wire. Tightened new serpentine belt. Had battery and alternator checked again, this time on Jeep and things seemed good. Print out still indicated battery needed to be replaced at some point 700CCA reading 680 CCA.
Well finally replaced battery with 690CCA one. Checked with car off 12.78 volts and when starated 113.36 volts. Problem still there. Gauge continues to jumps to 19v intermittently.
Finally to try and get reading of charging system when problem occurred, I hooked up some long leads attached to battery to my multimeter inside car.
Found while driving 55mph about 1800 rpm (always around this area problem starts) 14.28,14.32,14.35,14.51,14.56,14.30, 14.59 meter reading. When gauge pinned out at 19volts my multimeter readings 14.58, 14.62,14.5,14.64.
I did not see multimeter moment gauge pinned, but within seconds saw numbers around above. Gauge dropped back to normal (around 14 v) within a few minutes. Sitting at idle at stop light saw 14.03, 14.09,14.07 readings on multimeter.
So it appears gauge in car jumps to 19v but actual charging system in 14.6 v range.
Question what is causing gauge in car to jump to 19v and then return to "normal"? I understand a normal charging voltage would be 13.9 to 15.1.
I think I mentioned alternator has crack between 2 cooling slots. That does not concern me but how it got cracked does. I don't know if something in alternator (like rectifier diode) acting up on occassion. Denso alternator. I have to believe original.