The battery light in my 2002 GMC sierra stays on while I am driving. The battery has been changed. What can I check/fix myself before taking it to a mechanic. The battery indicator shows the power above the 14 volt mark and never goes below that. What I can I do? I was recently divorced and my ex used to take care of all of our vehicle maintenance issues, no I am on my own. Can you Help?
The 14 volts is what the charging output is, not the battery condition. Your battery voltage will be indicated on the gauge when the engine is not running. Check cables and connections first.
Most chain auto parts stores (Pep Boys, Advance, Auto Zone, Etc.) will test batteries and alternators for free. They commonly install batteries for no charge as well when you buy the battery. I would not let a chain store try to install an alternator or diagnose other problems–that is for an independent mechanic or GM dealer.
It is a little strange that the warning light is on yet the charging system appears to be working ok since you say the voltage is around 14 volts, as it should be. One thing that may be causing this is a bad blocking diode in the alternator. If that is correct you will need to replace it. I would also suggest having a shop check for any AC voltage across the battery while running at around 1500 RPM. Any more than .1 volt of AC voltage means a new alternator is needed also.
Had some of the guys I work with check the battery while I was working, cable was loose on the negative side. Battery was fine. But light is still on. I will go to advance or Napa and see what they say.