depends on if it's the new rp23 with the kashima coating or not. used to be off, or on with a stiffness setting of 1, 2, or 3. the new one is always on, either 0, 1, or 2, and then you can put it "on" to 3.

there should be a little picture on the front of the shock itself.

if the numbers are 1,2, and 3, then it is off (full suspension) or on (stiff). the number lined up with the lever is the stiffness. if the numbers are 0, 1, and 2, then it's always on. again, the stiffness is whatever number is lined up with the lever.

i always ride with mine off. i don't use it, my bike climbs rather well and is stiff enough without it.