Do you have a voltage regulator installed? With a 12.5 volt reading with the motor running the alternator is not charging.
answer that and we'll go from there.
I drew a picture, you will need to trace some wires, I don't know GM color codes. The idiot light wire may come from a buss in the fuse box, the important thing is that the side that goes out to the motor needs to be hooked to the regulator as shown.
The diode may not be necessary with an external regulator, if the car runs on after you shut the key then you need a diode.
my signature lines...not really directed at anyone in particular..
BE different....ACT normal.
No one is completely useless..They can always be used as a bad example
Last edited by powerrodsmike; 03-14-2009 at 10:25 PM.