2007 Hummer H3 Owner's Manual - Page 112

Notice: Operating your vehicle in Four-Wheel-Low Lock above 30 mph (48 km/h) for any extended period of time could cause damage to the transfer case. Do not operate your vehicle in Four-Wheel-Low Lock above 30 mph (48 km/h) for extended periods. 4 n Q (Four-Wheel-Low Lock): This mode delivers extra torque to all four wheels and is used for extreme off-road conditions. You might choose 4-Wheel-Low Lock if you are driving in off-road situations, such as, deep sand, mud, or snow and climbing or descending steep hills. If the vehicle has a locking rear axle, when in this mode you can also choose to lock the rear axle for additional traction in extreme off-road situations. See Locking Rear Axle on page 243. Indicator lights in the buttons show which mode you are in. The indicator lights will come on briefly when you turn on the ignition the mode the vehicle is in will stay on. If the lights do not come on, you should take your vehicle to your dealer for service. An indicator light will flash while shifting the transfer case. It will remain lit when the shift is complete. If for some reason the transfer case cannot make a requested shift, it will return to the last chosen setting. If the SERV 4WD message on the Driver Information Center (DIC) stays on, you should take your vehicle to your dealer for service. See Service 4WD message under DIC Warnings and Messages on page 196. Shifting between Four-Wheel High and Four-Wheel-High Lock With the vehicle traveling less than 45 mph (72 km/h), press and release the Four-Wheel High or Four-Wheel-High Lock button. The indicator light will flash while shifting. It will remain lit when the shift is complete. It may be necessary to drive backwards while turning for a distance of 25 feet (7.5 m) to get the lock feature to disengage. 112