2007 Hummer H3 Owner's Manual - Page 243

Locking Rear Axle Your vehicle may have this feature. The locking rear axle can give your vehicle additional traction from the rear wheels when traveling in off-road situations such as mud, snow, sand, steep hills and uneven terrain. The button used to turn this feature on or off is located to the right of the transfer case buttons on the center of the instrument panel. To lock the rear axle, do the following: 1. Place the transfer case in the 4LO Lock mode. This is the only mode which will allow the rear axle to lock. See Full-Time Four-Wheel Drive on page 111 for more information regarding the transfer case and 4LO Lock mode. 2. Press the button with the vehicle stopped or moving less than 2 mph (3 km/h). You must wait for the light in the button to stop flashing and remain illuminated before the rear axle is locked. Notice: If you try to lock the rear axle while your vehicle is stuck and the tires are spinning, you could damage your vehicle's drivetrain. The repairs would not be covered by your warranty. Always lock the rear axle before attempting situations and/or navigating terrain which could possibly cause the vehicle to become stuck. The locking rear axle will be disengaged when the wheel speed is greater than 20 mph (32 km/h), if the vehicle's battery is low and/or the transfer case is shifted out of 4LO Lock mode. Notice: If you lock the rear axle while driving on pavement, you could damage your vehicle's drivetrain. The repairs would not be covered by your warranty. Do not use the locking rear axle on pavement. If you need four-wheel drive when traveling on pavement, use only 4HI. 243