Hummer 2003 H2 Owner's Manual page 251

For mounds, washouts, loose up
-
hill slopes, ditches, etc.
When wheel spin occurs as the vehicle is moving, the
driver may notice a slight shaking or shuddering of the
vehicle. This is the indication that a loss of traction is
occurring on this terrain. The operator should:
1. Reduce throttle.
2. Assess the terrain properly and adjust vehicle speed
and gear ranges accordingly, 4HI or 4HI Lock
position for higher speed, 4LO Lock for more torque
and lower speeds.
3. Apply slight pressure to the brake when the shaking
or shuddering sensation is felt, keeping the vehicle
moving at a constant and controlled speed.
4. Be prepared to modulate the brake and throttle
through the adverse terrain.
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