GMC Sierra Owners Manual
Driving Characteristics and Towing Tips
Pulling a Trailer
Important points for pulling a trailer:
There are many different laws, including speed limit restrictions, having to do with trailering.
Make sure the rig will be legal, not only where you live but also where you will be driving.
A good source for this information can be state or provincial police.
Consider using a sway control.
See Hitches under Towing Equipment on page 9‑100.
Do not tow a trailer at all during the first 800 km (500 miles) the new vehicle is driven. The engine, axle, or other parts could be damaged.
During the first 800 km (500 miles) that a trailer is towed, do not drive over 80 km/h (50 mph) and do not make starts at full throttle. This helps the engine and other parts of the vehicle wear in at the heavier loads.
Vehicles can tow in D (Drive).
Shift the transmission to a lower gear if the transmission shifts too often under heavy loads and/ or hilly conditions.
Important considerations that have to do with weight:
Weight of the trailer
Weight of the trailer tongue
Weight on the vehicle's tires
Weight of the trailering combination
Driving with a Trailer
When towing a trailer, exhaust gases may collect at the rear of the vehicle and enter if the liftgate, trunk/hatch, or rear-most window is open.
Engine exhaust contains Carbon Monoxide (CO) which cannot be seen or smelled. It can cause unconsciousness and even death.
To maximize safety when towing a trailer:
Have the exhaust system inspected for leaks and make necessary repairs before starting a trip.
Never drive with the liftgate, trunk/hatch, or rear-most window open.
Fully open the air outlets on or under the instrument panel.
Adjust the Climate Control system to a setting that brings in only outside air and set the fan speed to the highest setting. See Climate Control System in the Index.
For more information about Carbon Monoxide, see Engine Exhaust on page 9‑36.
Towing a trailer requires a certain amount of experience. The combination you are driving is longer and not as responsive as the vehicle itself. Get acquainted with the handling and braking of the rig before setting out for the open road.
Before starting, check all trailer hitch parts and attachments, safety chains, electrical connectors, lamps, tires, and mirrors. If the trailer has electric brakes, start the combination moving and then apply the trailer brake controller by hand to be sure the brakes work.
During the trip, check occasionally to be sure that the load is secure and the lamps and any trailer brakes still work.
Stay at least twice as far behind the vehicle ahead as you would when driving the vehicle without a trailer.
This can help to avoid heavy braking and sudden turns.
More passing distance is needed when towing a trailer. The combination will not accelerate as quickly and is longer so it is necessary to go much farther beyond the passed vehicle before returning to the lane.
Hold the bottom of the steering wheel with one hand. To move the trailer to the left, move that hand to the left. To move the trailer to the right, move your hand to the right.
Always back up slowly and, if possible, have someone guide you.
Notice: Making very sharp turns while trailering could cause the trailer to come in contact with the vehicle. The vehicle could be damaged. Avoid making very sharp turns while trailering.
When turning with a trailer, make wider turns than normal. Do this so the trailer will not strike soft shoulders, curbs, road signs, trees, or other objects. Avoid jerky or sudden maneuvers. Signal well in advance.
If the trailer turn signal bulbs burn out, the arrows on the instrument panel will still flash for turns. It is important to check occasionally to be sure the trailer bulbs are still working.
Driving on Grades
Reduce speed and shift to a lower gear before starting down a long or steep downgrade. If the transmission is not shifted down, the brakes might get hot and no longer work well.
Vehicles can tow in D (Drive). Shift the transmission to a lower gear if the transmission shifts too often under heavy loads and/or hilly conditions.
The Tow/Haul Mode may be used if the transmission shifts too often.
See Tow/Haul Mode on page 9‑42.
When towing at high altitude on steep uphill grades, consider the following: Engine coolant will boil at a lower temperature than at normal altitudes. If the engine is turned off immediately after towing at high altitude on steep uphill grades, the vehicle may show signs similar to engine overheating. To avoid this, let the engine run while parked, preferably on level ground, with the automatic transmission in P (Park) for a few minutes before turning the engine off. If the overheat warning comes on, see Engine Overheating on page 10‑23.
Parking on Hills
Parking the vehicle on a hill with the trailer attached can be dangerous. If something goes wrong, the rig could start to move.
People can be injured, and both the vehicle and the trailer can be damaged. When possible, always park the rig on a flat surface.
If parking the rig on a hill:
1. Press the brake pedal, but do not shift into P (Park) yet. Turn the wheels into the curb if facing downhill or into traffic if facing uphill.
2. Have someone place chocks under the trailer wheels.
3. When the wheel chocks are in place, release the regular brakes until the chocks absorb the load.
4. Reapply the brake pedal. Then apply the parking brake and shift into P (Park).
5. If the vehicle is four-wheel-drive, be sure the transfer case is in a drive gear and not in N (Neutral).
6. Release the brake pedal.
It can be dangerous to get out of the vehicle if the shift lever is not fully in P (Park) with the parking brake firmly set. The vehicle can roll.
If the engine has been left running, the vehicle can move suddenly. You or others could be injured. To be sure the vehicle will not move, even when on fairly level ground, use the steps that follow.
Always put the shift lever fully in P (Park) with the parking brake firmly set.
If the transfer case on a four-wheel-drive vehicle is in N (Neutral), the vehicle will be free to roll, even if the shift lever is in P (Park). Be sure the transfer case is in a drive gear not in N (Neutral).
Leaving After Parking on a Hill
1. Apply and hold the brake pedal.
2. Start the engine.
3. Shift into a gear.
4. Release the parking brake.
5. Let up on the brake pedal.
6. Drive slowly until the trailer is clear of the chocks.
7. Stop and have someone pick up and store the chocks.
Maintenance when Trailer Towing
The vehicle needs service more often when pulling a trailer. See Maintenance Schedule on page 11‑3. Things that are especially important in trailer operation are automatic transmission fluid, engine oil, axle lubricant, belts, cooling system, and brake system. It is a good idea to inspect these before and during the trip.
Check periodically to see that all hitch nuts and bolts are tight.