I was looking over my engine and I noticed that the belt is not all the way on the pulley thats right next to/beneath the alternator. What does this pulley control? how can I get it back on all the way. I tried using my hands to slide it over but the belt is too tense

 

TTT

 

powersteering, take a 1/2" socket on a ratchet and turn the tensioner (near the crank pulley) downward. like you are tightening it, that will relieve pressure off the belt