Alternator and amp gauge question

#1
98 TJ with 4.0 and automatic, check gauge light came on today at lunch, looked at the amp gauge and it was almost at zero. Pulled over and popped the hood, didn’t see anything. Went to start it back up and the gauge was at almost 12 It stayed like that for about two miles then started going down again. Went to Advance Auto Parts to have charging system checked. The battery checked low but ok. The alternator was putting out over 13. Started it back up at Advance and the gauge went back up again and this time the check gauge light went out. Went about ½ mile and it came back on. I took it to the house and will investigate after work. Anyone have an idea where to start?
 
#2
when the voltage regulator in my alternator went out it would do that, mine showed voltage off the charts going to tellico one time. We replaced the alternator in the campsite and it fixed the issue.
 
#3
from what the FSM says the voltage regulator is in the PCM on the 98s. I have read that cable connections need to be very clean and tight, this afternoon I will start checking them.
 
#4
Here’s an update. I went through and cleaned all cable ends, both positive and negative and made sure everything was tight. I took the PCM connections loose and scrubbed them with a dry tooth brush. As of right now it is working fine.
 
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