Nothing electrical...That system is entirely mechanical. Only the position sensor and indicator parts are electrical. Both axles have to turn a bit until the pawl lines up to lock the diff so that's why it's freewheeling with only one side up.
Here are some tips to keep in mind when making adjustments:
a) Tension on the cables is actually pulling the diff OUT of lock mode. A loose cable adjustment will leave the diff locked.
b) One of the cables entering the box comes from the 2wd/4wd shifter...it will RELEASE tension when moved to any position besides Turf mode, allowing the rear diff to lock. The other cable comes from the P,R,N,H,L shifter...it will RELEASE tension when moved to Park, allowing the diff to lock when in Park, even when in Turf mode-(safety measure especially on uneven terrain).
I don't think you need to bring it in to a dealer. Look in that box while moving your shifters and you'll see and understand the mechanicals of it. The principle of it is, either one, or both at the same time, of the two shifters can release tension on the same cable coming out of the rear of the box, which allows the diff to lock. If adjusted properly, the only time both cables are under tension, pulling the diff out of lock is in Turf mode AND out of park simultaneously.