I have an 03 F250 7.3L single alternator setup. The truck was purchased on the 15 Jan 11. Truck came with two brand new Interstate batteries.
The other day I noticed the ABS light on and then the truck wouldn't start that afternoon. I had the alternator check and it was bad. Replaced it, said it tested and only 12.5 volts on low charged batteries. Charged both batteries overnight, still only reading 12.5 volts. Checked the voltage on the back of the alternator and only 12.5 volts. Pulled the plug on the alternator and only the or/b wire had power. The white/yel wire read zero. Jumpered that that w/y wire post to battery and the alternator began putting out 14.3v.
My question is where does that wire get power from? Is that a problem?