2004 Hummer H2 Owner's Manual - Page 106

This mode delivers extra torque to all four wheels and is used for extreme off-road conditions. You might choose 4LO Lock if you are driving off-road, deep sand, mud, or snow and climbing or descending steep hills. 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 4-11. Notice: Operating your vehicle in 4LO Lock above 50 mph (80 km/h) for any extended period of time could cause damage to the transfer case. Do not operate your vehicle in 4LO Lock above 50 mph (80 km/h) for extended periods. I(4LO Lock): N (NEUTRAL): Shift the vehicle's transfer case to NEUTRAL only when towing your vehicle. See Recreational Vehicle Towing on page 4-65 or Towing Your Vehicle on page 4-65 for more information. Indicator lights in the buttons show which mode you are in. The indicator lights will come on briefly when you turn on the ignition and one 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 illuminated 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 SERVICE 4WD message stays on, you should take your vehicle to your dealer for service. See "Service 4WD message" under Driver Information Center (DIC) on page 3-44. {CAUTION: Shifting the transfer case to NEUTRAL can cause your vehicle to roll even if the transmission is in PARK (P). You or someone else could be seriously injured. Be sure to set the parking brake before placing the transfer case in NEUTRAL. See Parking Brake on page 2-29. 2-26