My volt meter was running below 12V if any load was put on the engine, and seems to pick its own voltage between 12 and 13.5 otherwise (avg 12.5). I got a new interstate battery and alternator. It stays above 12 now, but still picks its own voltage. Voltage still hugs 12 if load (lights, A/C, rear defrost, etc) is turned on. The voltage regulator is internal in the alternator, so I don't know what to do. It should be up around 14 and stay there all the time. Thoughts?

 

Check all the ground and upgrade them

 

Check your alternator! before you fry anything.. i came dangerously close. Internal regulators go bad so just test it again. Or like swanton said u have a bad ground and its draining power.

 

Make sure the small plug is attached to the back of the alternator. IF it is, then pull it off anc with the key to ON, check for voltage on the Black/White wire. If it is not there, check the fuse that feeds it.

Usually on a series four, even with that connector off, the alt will put out if the engine is rev'd to over 2000 rpm or so.