Longshot, ignore cuddy. He's obviously behind on his meds.
Not familiar with the 1500, I'd recommend you pull out the Owner's Manual and see what the recommended adjustment is, and how it is accomplished.
Looking at a picture, it appears you will find an adjustable collar at the bottom of the shock. Cranking it around with either a special spanner or a big crescent wrench will increase (or decrease) the preload of the spring. It doesn't look like you have any damping adjustment.