GMC Sierra Owners Manual
Four-wheel-drive vehicles can be used for off-road driving. Vehicles without four-wheel drive and vehicles not equipped with All Terrain (AT) or On-Off Road (OOR) tires must not be driven off-road except on a level, solid surface. To contact the tire manufacturer for more information about the original equipment tires, see the Limited Warranty and Owner Assistance Information manual.
Controlling the vehicle is the key to successful off-road driving. One of the best ways to control the vehicle is to control the speed.
When driving off-road, bouncing and quick changes in direction can easily throw you out of position. This could cause you to lose control and crash. You and your passengers should always wear safety belts.
Before Driving Off-Road
• Have all necessary maintenance and service work completed.
• Fuel the vehicle, fill fluid levels, and check inflation pressure in all tires, including the spare, if equipped.
• Read all the information about four-wheel-drive vehicles in this manual.
• Make sure all underbody shields, if equipped, are properly attached.
• Know the local laws that apply to off-road driving.
To gain more ground clearance if needed, it may be necessary to remove the front fascia lower air dam.
Notice: Operating the vehicle for extended periods without the front fascia lower air dam installed can cause improper air flow to the engine. Re-attach the front fascia air dam after off-road driving.
Loading the Vehicle for Off-Road Driving
• Unsecured cargo on the load floor can be tossed about when driving over rough terrain. You or your passengers can be struck by flying objects. Secure the cargo properly.
• Keep cargo in the cargo area as far forward and as low as possible. The heaviest things should be on the floor, forward of the rear axle.
• Heavy loads on the roof raise the vehicle's center of gravity, making it more likely to roll over. You can be seriously or fatally injured if the vehicle rolls over. Put heavy loads inside the cargo area, not on the roof.
For more information about loading the vehicle, see Vehicle Load Limits and Tires.
• Always use established trails, roads, and areas that have been set aside for public off-road recreational driving and obey all posted regulations.
• Do not damage shrubs, flowers, trees, or grasses or disturb wildlife.
• Do not park over things that burn. See Parking Over Things that Burn..
Driving on Hills
Driving safely on hills requires good judgment and an understanding of what the vehicle can and cannot do.
If the vehicle has the two-speed automatic transfer case, shifting the transfer case to N (Neutral) can cause your vehicle to roll even if the transmission is in P (Park) for an automatic transmission or any gear position for a manual transmission. This is because the N (Neutral) position on the transfer case overrides the transmission. You or someone else could be injured. If leaving the vehicle, set the parking brake and shift the transmission to P (Park) for an automatic transmission or any gear position for a manual transmission. Shift the transfer case to any position but N (Neutral).
Before driving on a hill, assess the steepness, traction, and obstructions. If the terrain ahead cannot be seen, get out of the vehicle and walk the hill before driving further.
When driving on hills:
• Use a low gear and keep a firm grip on the steering wheel.
• Maintain a slow speed.
• When possible, drive straight up or down the hill.
• Slow down when approaching the top of the hill.
• Use headlamps even during the day to make the vehicle more visible.
Driving to the top of a hill at high speed can cause an accident.
There could be a drop-off, embankment, cliff, or even another vehicle. You could be seriously injured or killed. As you near the top of a hill, slow down and stay alert.
• Never go downhill forward or backward with either the transmission or transfer case in N (Neutral). The brakes could overheat and you could lose control.
If the vehicle has the two-speed automatic transfer case, shifting the transfer case to N (Neutral) can cause your vehicle to roll even if the transmission is in P (Park). This is because the N (Neutral) position on the transfer case overrides the transmission. You or someone else could be injured. If leaving the vehicle, set the parking brake and shift the transmission to P (Park). Shift the transfer case to any position but N (Neutral).
• When driving down a hill, keep the vehicle headed straight down. Use a low gear because the engine will work with the brakes to slow the vehicle and help keep the vehicle under control.
Heavy braking when going down a hill can cause your brakes to overheat and fade. This could cause loss of control and you or others could be injured or killed.
Apply the brakes lightly when descending a hill and use a low gear to keep vehicle speed under control.
If the vehicle stalls on a hill:
1. Apply the brakes to stop the vehicle, and then apply the parking brake.
2. Shift into P (Park) for an automatic transmission or 1 (First) for a manual transmission and then restart the engine.
• If driving uphill when the vehicle stalls, shift to R (Reverse), release the parking brake, and back straight down.
• Never try to turn the vehicle around. If the hill is steep enough to stall the vehicle, it is steep enough to cause it to roll over.
• If you cannot make it up the hill, back straight down the hill.
• Never back down a hill in N (Neutral) using only the brake.
• The vehicle can roll backward quickly and you could lose control.
• If driving downhill when the vehicle stalls, shift to a lower gear, release the parking brake, and drive straight down the hill.
3. If the vehicle cannot be restarted after stalling, set the parking brake, shift an automatic transmission into P (Park) or a manual transmission into 1 (First), and turn the vehicle off.
3.1. Leave the vehicle and seek help.
3.2. Stay clear of the path the vehicle would take if it rolled downhill.
• Avoid turns that take the vehicle across the incline of the hill.
A hill that can be driven straight up or down might be too steep to drive across. Driving across an incline puts more weight on the downhill wheels which could cause a downhill slide or a rollover.
• Surface conditions can be a problem. Loose gravel, muddy spots, or even wet grass can cause the tires to slip sideways, downhill. If the vehicle slips sideways, it can hit something that will trip it – a rock, a rut, etc. – and roll over.
• Hidden obstacles can make the steepness of the incline more severe. If a rock is driven across with the uphill wheels, or if the downhill wheels drop into a rut or depression, the vehicle can tilt even more.
• If an incline must be driven across, and the vehicle starts to slide, turn downhill. This should help straighten out the vehicle and prevent the side slipping.
Getting out of the vehicle on the downhill side when stopped across an incline is dangerous.
If the vehicle rolls over, you could be crushed or killed. Always get out on the uphill side of the vehicle and stay well clear of the rollover path.
Driving in Mud, Sand, Snow, or Ice
Use a low gear when driving in mud – the deeper the mud, the lower the gear. Keep the vehicle moving to avoid getting stuck.
Traction changes when driving on sand. On loose sand, such as on beaches or sand dunes, the tires tend to sink into the sand. This affects steering, accelerating, and braking. Drive at a reduced speed and avoid sharp turns or abrupt maneuvers.
Traction is reduced on hard packed snow and ice and it is easy to lose control. Reduce vehicle speed when driving on hard packed snow and ice.
Driving on frozen lakes, ponds, or rivers can be dangerous. Ice conditions vary greatly and the vehicle could fall through the ice; you and your passengers could drown. Drive your vehicle on safe surfaces only.
Driving in Water
Driving through rushing water can be dangerous. Deep water can sweep your vehicle downstream and you and your passengers could drown. If it is only shallow water, it can still wash away the ground from under your tires.
Traction could be lost, and the vehicle could roll over. Do not drive through rushing water.
Notice: Do not drive through standing water if it is deep enough to cover the wheel hubs, axles or exhaust pipe. Deep water can damage the axle and other vehicle parts.
If the standing water is not too deep, drive slowly through it. At faster speeds, water splashes on the ignition system and the vehicle can stall. Stalling can also occur if you get the exhaust pipe under water.
While the exhaust pipe is under water, you will not be able to start the engine. When going through water, the brakes get wet, and it might take longer to stop. See Driving on Wet Roads.
After Off-Road Driving
Remove any brush or debris that has collected on the underbody or chassis, or under the hood. These accumulations can be a fire hazard.
After operation in mud or sand, have the brake linings cleaned and checked. These substances can cause glazing and uneven braking.
Check the body structure, steering, suspension, wheels, tires, and exhaust system for damage and check the fuel lines and cooling system for any leakage.
More frequent maintenance service is required. Refer to the Maintenance Schedule for more information.