I have a 2000 Dodge Dakota and when I crank it up it seems to run fine. After about five minutes the volt gauge (battery) goes all the way
down, and the check gauges light comes on. It also threw the belt off. I thought it was the alternator so I replaced it. The truck is still doing the same thing. I hope some one can help.

 

try checking the belt tensioner

 

If the belt came off definitely look at the tensioner. The belt wasn't tight enough to turn the alternator thus the low charge. Also if tensioner is bad and not fixed, your water pump won't turn correctly (overheat possiblity) and your steering will get tight without the P/S pump turning correctly.