My volt meter moves back and forth from 13-15 volts. While driving at night, my head lights flicker. I took my pickup into my dealer here in town, but they told me everything is ok.

 

Alternator

 

the voltmeter used to fluctuate with the signals on the older gens but definitely no headlamp flicker....I'm with kevinkpk...bad voltage regulator/alternator can cause this. No way a computer controlled charging system should switch like that. If you got warranty...take it back and have the shop foreman involved.