Front 4X4 hubs

Hubs wont lock, fuse is okay, floor shift for transfer case, unit shifts to 4hi and 4low and 2 hi, front shaft powers and wheel shafts out of pumpkin spin, what engages the hubs? Wires to wheel assembly seem intact. Wire assembly seem to terminate at brain box under hood-must not be getting signal to engage hubs. Confused and Thank You!