battery light comes on

2001 GMC SIERRA
350,000 MILES
Avatar
SUKH1782
  • MEMBER
  • 2 POSTS
I just changed the alternator now the battery is charging, however the gauge drops down to 14 the goes back up and down. the battery light comes on the goes off when the gauge goes up. I have the battery on charger right now. I thought maybe the battery was low as I did drive to get the alternator replaced .
Feb 16, 2012 at 6:24 PM
Advertisement
Avatar
BILLYMAC
  • CERTIFIED EXPERT
  • 2,204 POSTS
Hi
first you need to take a volt meter and check the alternator for output it should read exactly the same as your guage on the dash if different the guage is wrong if the guage gets the wrong reading the light will come on. if the guage reads same as volt meter prob will be the new alternator . However at 14 volts the light should not be on.
Feb 16, 2012 at 6:30 PM
Avatar
SUKH1782
  • MEMBER
  • 2 POSTS
Thank you for your answer. I was wrong it's not 14 its under 12
Feb 16, 2012 at 6:48 PM
Advertisement
Avatar
BILLYMAC
  • CERTIFIED EXPERT
  • 2,204 POSTS
ok yes then that is a problem your new alternator is not working it seems like the internal regulator has a problem.
Feb 16, 2012 at 6:56 PM