My Gen light went on after I'd removed the alternator to change out the thermostat. Bugged me in that not all the connections were tight. After tightening them all I drove for less than 5 minutes. The Gen light returned yet this time the in dash voltmeter dropped and stays at 12 volts as opposed to the 14 before. I had the alternator bench tested. It passed. Any thoughts?

 

Have you tried resetting the pcm?

 

check your connections and your main inline fuse in the power box beside the battery.

12v indicates your alternator is not charging your battery, and its a matter of time before it dies. 12 - 11 - 10 - 9 ..... dead.