Originally Posted by Jingoist
I just did a cold start right now, voltage was 12.58 cold, batteries went down to 10.60 while cranking, hit 12.2 until the alternator kicked in and then went up to 14. There was no battery light this time.
These voltages were all taken on the battery terminals. And like I said before, once I start driving the light never comes back on.
Is there a way to test the voltage regulator?
Yes, pull the alternator out and have it tested by a reputable alternator repair shop. Don't go to those autopart stores, their tests only last 5-10 seconds and our regulators show problems after that time, so their tests never show it.
I know it's not what you want to hear right now, especially after dropping a few hundred on new batteries. But we have been through this before and it ends up being the alternator. I chased and tightened grounds, replaced batteries, and had to go through 3 different alternators (autozone duralast crap) before the problem was solved. Save yourself time, effort, and headache and go get your alternator repaired or replaced. Try and stay with a Motorcraft alternator...