Had trouble with this myself. Take passenger wheel off. Jack up van. 13 mm box wrench on the tensioner. Crank counter clockwise as far as you can. I wedged a wood block in to hold the tension on the wrench. KEY STEP: MAKE SURE THe BELT is ROUTED PROPERLY. I didn't have the sketch under the hood so I went to the dealer. Route the belt over all accessories except the idler pulley. Give a good tug on the belt where it goes from the P/S pump to the alternator and wrap it around the idler or water pump if easier. Proper routing is a must!