Gauge on dash board for charging reads minus pegs the left when light’s get6 turned on
Have the alternator and battery tested. I suspect your alternator is failing.
Pretty generic answer it’s new. And charging I’m thinking voltage regulator. Or any other suggestions ???
Was gauge working before you changed alternator?
Often, a “generic answer” is a good starting point in solving a problem, and can rule out simple issues, before moving on to more complex troubleshooting. Have you had the battery tested?