[Z06RB]

Originally Posted by H2ummer

From Hummer...
The integrated Borg-Warner two-speed electrically controlled full-time 4WD system is capable of further reducing the vehicle's gear ratios by 2.64:1 when necessary, for highly controlled obstacle climbing. It provides a 40/60 percent front-to-rear torque split in "High Open" mode or when the differentials are unlocked and a 50/50 percent front-to-rear power split when the transfer case differential is locked.

1) A high-range open or "4 HI Open" for normal, everyday driving on dry road surfaces at any speeds.

2) A high-range lock or "4 HI Locked" for semi-slippery surfaces like snow, light sand or wet areas, such as those around a boat launch; this selection locks the front and rear output shafts together, so their wheels rotate at exactly the same speed

Thanks for the info.