If its the same as a BX24 hold thottle down and pull up the little pull pin on right of steering column and let go of trottle and away you go at desired speed.
Tarheeler, the cruise on the L3400 is a lever connected to the foot HST pedal via a cable. It will only control forward movement, not reverse, and will reset to "0" if you step on the reverse side of the HST pedal or if you step on BOTH brake pedals at the same time. If you have the brake pedals "unlocked" to use for tighter turning then it will not reset. Hope this helps.
It's not like the BX24... To engage it, just push the lever forward... this is attached to a cable that is connected to the HST petal which actually moves the petal down (as if you were steeping on it) for forward motion.
If its the same as a BX24 hold thottle down and pull up the little pull pin on right of steering column and let go of trottle and away you go at desired speed.
WHAT?! I don't do it that way with mybx24. I push on hst pedal and push a hair more then desired speed, push down on the cruise pin and let go of the hst pedal. It locks everytime. I am not sure why you need to pull on the pin?
I just used it couple days ago when I was spreading fertilizer.