If the vehicle has a diesel engine, see the DURAMAX® Diesel manual for more information.

Caution:  The driver can lose control when pulling a trailer if the correct equipment is not used or the vehicle is not driven properly. For example, if the trailer is too heavy, the brakes may not work well -- or even at all. The driver and passengers could be seriously injured. The vehicle may also be damaged; the resulting repairs would not be covered by the vehicle warranty. Pull a trailer only if all the steps in this section have been followed. Ask your dealer/retailer for advice and information about towing a trailer with the vehicle.

Notice: Pulling a trailer improperly can damage the vehicle and result in costly repairs not covered by the vehicle warranty. To pull a trailer correctly, follow the advice in this section and see your dealer/retailer for important information about towing a trailer with the vehicle.

To identify the trailering capacity of the vehicle, read the information in "Weight of the Trailer" that appears later in this section.

Trailering is different than just driving the vehicle by itself. Trailering means changes in handling, acceleration, braking, durability and fuel economy. Successful, safe trailering takes correct equipment, and it has to be used properly.

The following information has many time-tested, important trailering tips and safety rules. Many of these are important for your safety and that of your passengers. So please read this section carefully before pulling a trailer.

Pulling A Trailer

Here are some important points:

Three important considerations have to do with weight:

Also see Tow/Haul later in this section for information about the Tow/Haul button and the Tow/Haul indicator light.

Weight of the Trailer

How heavy can a trailer safely be?

It depends on how the rig is used. For example, speed, altitude, road grades, outside temperature and how much the vehicle is used to pull a trailer are all important. It can depend on any special equipment on the vehicle, and the amount of tongue weight the vehicle can carry. See "Weight of the Trailer Tongue" later in this section for more information.

Maximum trailer weight is calculated assuming only the driver is in the tow vehicle and it has all the required trailering equipment. The weight of additional optional equipment, passengers and cargo in the tow vehicle must be subtracted from the maximum trailer weight.

Use the following chart to determine how much the vehicle can weigh, based upon the vehicle model and options.

Vehicle	Axle Ratio	Maximum Trailer Weight	GCWR*
G1500 Cargo Van 2WD
4.3L V6	3.42	4,400 lbs (1 996 kg)	9,500 lbs (4 309 kg)
5.3L V8	3.42 3.73	6,700 lbs (3 039 kg)	12,000 lbs (5 443 kg)
H1500 Cargo Van AWD
5.3L V8	3.42	6,500 lbs (2 948 kg)	12,000 lbs (5 443 kg)
G1500 Passenger Van 2WD
5.3L V8	3.73	6,200 lbs (2 812 kg)	12,000 lbs (5 443 kg)
H1500 Passenger Van AWD
5.3L V8	3.73	6,000 lbs (2 722 kg)	12,000 lbs (5 443 kg)
G2500 Cargo Van 2WD Short Wheelbase
4.8L V8	3.73 4.10	6,400 lbs (2 903 kg) 7,400 lbs (3 357 kg)	12,000 lbs (5 443 kg) 13,000 lbs (5 897 kg)
6.0L V8	3.73 4.10	8,400 lbs (3 810 kg) 10,000 lbs (4 536 kg)	14,000 lbs (6 350 kg) 16,000 lbs (7 257 kg)
G2500 Cargo Van 2WD Long Wheelbase
4.8L V8	3.73 4.10	6,200 lbs (2 812 kg) 7,200 lbs (3 266 kg)	12,000 lbs (5 443 kg) 13,000 lbs (5 897 kg)
6.0L V8	3.73 4.10	8,200 lbs (3 719 kg) 10,000 lbs (4 536 kg)	14,000 lbs (6 350 kg) 16,000 lbs (7 257 kg)
G2500 Passenger Van 2WD Short Wheelbase
6.0L V8	3.73	7,600 lbs (3 447 kg)	14,000 lbs (6 350 kg)
6.0L V8	4.10	9,600 lbs (4 355 kg)	16,000 lbs (7 257 kg)
G3500 Cargo Van 2WD Short Wheelbase
4.8L V8	3.73 4.10	6,400 lbs (2 903 kg) 7,400 lbs (3 295 kg)	12,000 lbs (5 443 kg) 13,000 lbs (5 897 kg)
6.0L V8	3.73 4.10	8,400 lbs (3 810 kg) 10,000 lbs (4 536 kg)	14,000 lbs (6 350 kg) 16,000 lbs (7 257 kg)
G3500 Cargo Van 2WD Long Wheelbase
4.8L V8	3.73 4.10	6,100 lbs (2 767 kg) 7,100 lbs (3 221 kg)	12,000 lbs (5 443 kg) 13,000 lbs (5 897 kg)
6.0L V8	3.73 4.10	8,200 lbs (3 719 kg) 10,000 lbs (4 536 kg)	14,000 lbs (6 350 kg) 16,000 lbs (7 257 kg)
G3500 Passenger Van 2WD Short Wheelbase
6.0L V8	3.73	7,600 lbs (3 447 kg)	14,000 lbs (6 350 kg)
G3500 Passenger Van 2WD Long Wheelbase
6.0L V8	3.73	7,300 lbs (3 311 kg)	14,000 lbs (6 350 kg)
*The Gross Combined Weight Rating (GCWR) is the total allowable weight of the completely loaded vehicle and trailer including any passengers, cargo equipment and conversion. The GCWR for the vehicle should not be exceeded.

Ask your dealer/retailer for our trailering information or advice, or write us at our Customer Assistance Offices. See Customer Assistance Offices for more information.

Weight of the Trailer Tongue

The tongue load (A) of any trailer is an important weight to measure because it affects the total gross weight of the vehicle. The Gross Vehicle Weight (GVW) includes the curb weight of the vehicle, any cargo carried in it, and the people who will be riding in the vehicle. If there are a lot of options, equipment, passengers or cargo in the vehicle, it will reduce the tongue weight the vehicle can carry, which will also reduce the trailer weight the vehicle can tow. If towing a trailer, the tongue load must be added to the GVW because the vehicle will be carrying that weight, too. See Loading the Vehicle for more information about the vehicle's maximum load capacity.

The trailer tongue weight (A) should be 10 percent to 15 percent of the total loaded trailer weight (B), up to a maximum of 400 lbs (181 kg) with a weight carrying hitch. The trailer tongue weight (A) should be 10 percent to 15 percent of the total loaded trailer weight (B), up to a maximum of 1,000 lbs (454 kg) with a weight distributing hitch.

Do not exceed the maximum allowable tongue weight for the vehicle. Choose the shortest hitch extension that will position the hitch ball closest to the vehicle. This will help reduce the effect of trailer tongue weight on the rear axle.

After loading the trailer, weigh the trailer and then the tongue, separately, to see if the weights are proper. If they are not, adjustments might be made by moving some items around in the trailer.

Trailering may be limited by the vehicle's ability to carry tongue weight. Tongue weight cannot cause the vehicle to exceed the GVWR (Gross Vehicle Weight Rating) or the RGAWR (Rear Gross Axle Weight Rating). The effect of additional weight may reduce the trailering capacity more than the total of the additional weight.

Consider the following example:

A vehicle model base weight is 5,500 lbs (2 495 kg); 2,800 lbs (1 270 kg) at the front axle and 2,700 lbs (1 225 kg) at the rear axle. It has a GVWR of 7,200 lbs (3 266 kg), a RGAWR of 4,000 lbs (1 814 kg) and a GCWR (Gross Combination Weight Rating) of 14,000 lbs (6 350 kg). The trailer rating should be:

Expect tongue weight to be at least 10 percent of trailer weight (850 lbs (386 kg)) and because the weight is applied well behind the rear axle, the effect on the rear axle is greater than just the weight itself, as much as 1.5 times as much. The weight at the rear axle could be 850 lbs (386 kg) X 1.5 = 1,275 lbs (578 kg). Since the rear axle already weighs 2,700 lbs (1 225 kg), adding 1,275 lbs (578 kg) brings the total to 3,975 lbs (1 803 kg). This is very close to, but within the limit for RGAWR as well. The vehicle is set to trailer up to 8,500 lbs (3 856 kg).

If the vehicle has many options and there is a front seat passenger and two rear seat passengers with some luggage and gear in the vehicle as well. 300 lbs (136 kg) could be added to the front axle weight and 400 lbs (181 kg) to the rear axle weight. The vehicle now weighs:

Weight is still below 7,200 lbs (3 266 kg) and you might think 700 additional pounds (318 kg) should be subtracted from the trailering capacity to stay within GCWR limits. The maximum trailer would only be 7,800 lbs (3 538 kg). You may go further and think the tongue weight should be limited to less than 1,000 lbs (454 kg) to avoid exceeding GVWR. But the effect on the rear axle must still be considered. Because the rear axle now weighs 3,100 lbs (1 406 kg), 900 lbs (408 kg) can be put on the rear axle without exceeding RGAWR. The effect of tongue weight is about 1.5 times the actual weight. Dividing the 900 lbs (408 kg) by 1.5 leaves only 600 lbs (272 kg) of tongue weight that can be handled. Since tongue weight is usually at least 10 percent of total loaded trailer weight, expect that the largest trailer the vehicle can properly handle is 6,000 lbs (2 721 kg).

It is important that the vehicle does not exceed any of its ratings -- GCWR, GVWR, RGAWR, Maximum Trailer Rating or Tongue Weight. The only way to be sure it is not exceeding any of these ratings is to weigh the vehicle and trailer.

Total Weight on the Vehicle's Tires

Be sure the vehicle's tires are inflated to the upper limit for cold tires. These numbers can be found on the Certification label at the rear edge of the driver's door or see Loading the Vehicle. Make sure not to go over the GVW limit for the vehicle, or the GAWR, including the weight of the trailer tongue. If using a weight distributing hitch, make sure not to go over the rear axle limit before applying the weight distribution spring bars.

Hitches

It is important to have the correct hitch equipment. Crosswinds, large trucks going by and rough roads are a few reasons why the right hitch is needed.

Weight-Distributing Hitches and Weight Carrying Hitches

A: Body to Ground Distance

B: Front of Vehicle

When using a weight-distributing hitch, the hitch must be adjusted so the distance (A) remains the same both before and after coupling the trailer to the tow vehicle.

If a step-bumper hitch will be used, the bumper could be damaged in sharp turns. Make sure there is ample room when turning to avoid contact between the trailer and the bumper.

If the loaded trailer being pulled will weigh more than 5,000 lbs (2 270 kg), be sure to use a properly mounted weight-distributing hitch and sway control of the proper size. This equipment is very important for proper vehicle loading and good handling when driving. Always use a sway control if the trailer will weigh more than these limits. Ask a hitch dealer about sway controls.

Will any holes need to be made in the body of the vehicle when a trailer hitch is installed?

If using the wiring provided with the factory-installed trailering package, no holes need to be made in the body of the vehicle. However, if an aftermarket hitch is installed, holes may need to be made in the body.

If holes are made in the body, then be sure to seal the holes later when the hitch is removed. If the holes are not sealed, deadly carbon monoxide (CO) from the engine's exhaust can get into the vehicle as well as dirt and water. See "Carbon Monoxide" under Engine Exhaust.

Safety Chains

Always attach chains between the vehicle and the trailer. Cross the safety chains under the tongue of the trailer to help prevent the tongue from contacting the road if it becomes separated from the hitch. Always leave just enough slack so the rig can turn. Never allow safety chains to drag on the ground.

Tow/Haul Mode

Pressing this button at the end of the shift lever turns on and off the tow/haul mode.

This indicator light on the instrument panel cluster comes on when the tow/haul mode is on.

Tow/Haul is a feature that assists when pulling a heavy trailer or a large or heavy load. See Tow/Haul Mode for more information.

Tow/Haul is designed to be most effective when the vehicle and trailer combined weight is at least 75 percent of the vehicle's Gross Combined Weight Rating (GCWR). See "Weight of the Trailer" later in the section. Tow/Haul is most useful under the following driving conditions:

Operating the vehicle in Tow/Haul when lightly loaded or with no trailer at all will not cause damage. However, there is no benefit to the selection of Tow/Haul when the vehicle is unloaded. Such a selection when unloaded may result in unpleasant engine and transmission driving characteristics and reduced fuel economy. Tow/Haul is recommended only when pulling a heavy trailer or a large or heavy load.

Trailer Brakes

A loaded trailer that weighs more than 1,500 lbs (680 kg) needs to have its own brake system that is adequate for the weight of the trailer. Be sure to read and follow the instructions for the trailer brakes so they are installed, adjusted and maintained properly.

Driving with a Trailer

Caution: 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

Towing a trailer requires a certain amount of experience. Get to know the rig before setting out for the open road. Get acquainted with the feel of handling and braking with the added weight of the trailer. And always keep in mind that the vehicle you are driving is now longer and not as responsive as the vehicle is by itself.

Before starting, check all trailer hitch parts and attachments, safety chains, electrical connectors, lamps, tires and mirror adjustments. If the trailer has electric brakes, start the vehicle and trailer moving and then apply the trailer brake controller by hand to be sure the brakes are working. This checks the electrical connection at the same time.

During the trip, check occasionally to be sure that the load is secure, and that the lamps and any trailer brakes are still working.

Following Distance

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 situations that require heavy braking and sudden turns.

Passing

More passing distance is needed when towing a trailer. Because the rig is longer, it is necessary to go much farther beyond the passed vehicle before returning to the lane.

Backing Up

Hold the bottom of the steering wheel with one hand. Then, 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.

Making Turns

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.

Turn Signals When Towing a Trailer

The arrows on the instrument panel flash whenever signaling a turn or lane change. Properly hooked up, the trailer lamps also flash, telling other drivers the vehicle is turning, changing lanes or stopping.

When towing a trailer, the arrows on the instrument panel flash for turns even if the bulbs on the trailer are burned out. For this reason you may think other drivers are seeing the signal when they are not. 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 have to be used so much that they would get hot and no longer work well.

The vehicle 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.

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.

Parking on Hills

Caution: 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 the transmission 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 brake pedal until the chocks absorb the load.
4. Reapply the brake pedal. Then apply the parking brake and shift into P (Park).
5. Release the brake pedal.

Leaving After Parking on a Hill

1. Apply and hold the brake pedal while you:

•	start the engine,

•	shift into a gear, and

•	release the parking brake.

2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. 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 this manual's Maintenance Schedule or Index for more information. 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.

Trailer Wiring Harness

The optional heavy-duty trailer wiring package includes a wiring harness, with a seven-pin connector at the rear of the vehicle and a four-wire harness assembly under the driver side of the instrument panel. The four-wire harness assembly comes without a connector.

If the vehicle does not have a trailer hitch, the seven-wire harness assembly with connector is taped together and located in a frame pocket at the driver side rear left corner of the frame.

If the vehicle has a trailer hitch, the seven-wire harness assembly with connector is attached to a bracket on the hitch platform. In both cases, the seven-wire harness has a connector and includes a 30-amp feed wire.

The seven-wire harness connector contains the following trailer circuits:

The four-wire harness (without connector) contains the following circuits:

* If the vehicle is a cutaway with trailer provisions, a 15 amp fuse will be shared for both left/stop trailer turn and right/stop trailer turn signals. However, the cutaway lighting connector will have a 10 amp fuse for each signal.

** If the vehicle is a cutaway with trailer provisions, a 15 amp fuse will be shared for trailer park lamps and cutaway rear lighting connector park lamps. Also, a 10 amp fuse will be shared for trailer back-up lamps and cutaway rear lighting connector back-up lamps.

When towing at high elevation on steep uphill grades, consider the following:

Engine coolant at higher elevation will boil at a lower temperature than at or near sea level. If the engine is turned off immediately after towing at high elevation 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 transmission in P (Park) and the park brake applied for at least five minutes before turning the engine off. If the overheat warning comes on, see Engine Overheating.

Use one of the following charts to determine how much the vehicle can weigh, based upon your vehicle model and options.

Vehicle	Axle Ratio	Max. Trailer Wt.	GCWR**
C-2500 Extended Cab Standard Box HD -- 2WD*†	3.73	15,500 lbs (7 031 kg)	22,000 lbs (9 979 kg)
C-2500 Crew Cab Standard Box HD -- 2WD*†	3.73	15,300 lbs (6 940 kg)	22,000 lbs (9 979 kg)
C-2500 Regular Cab Long Box HD -- 2WD*†	3.73	15,800 lbs (7 167 kg)	22,000 lbs (9 979 kg)
C-2500 Extended Cab Long Box HD -- 2WD*†	3.73	15,300 lbs (6 940 kg)	22,000 lbs (9 979 kg)
C-2500 Crew Cab Long Box HD -- 2WD*†	3.73	14,500 lbs (6 577 kg)	22,000 lbs (9 979 kg)
K-2500 Extended Cab Standard Box HD -- 4WD*†	3.73	14,500 lbs (6 577 kg)	22,000 lbs (9 979 kg)
K-2500 Crew Cab Standard Box HD -- 4WD*†	3.73	13,900 lbs (6 305 kg)	22,000 lbs (9 979 kg)
K-2500 Regular Cab Long Box HD -- 4WD*†	3.73	15,500 lbs (7 031 kg)	22,000 lbs (9 979 kg)
K-2500 Extended Cab Long Box HD -- 4WD*†	3.73	13,800 lbs (6 260 kg)	22,000 lbs (9 979 kg)
K-2500 Crew Cab Long Box HD -- 4WD*†
Conventional Trailer	3.73	13,000 lbs (5 897 kg)	22,000 lbs (9 979 kg)
Fifth-Wheel Trailer	3.73	12,700 lbs (5 761 kg)	22,000 lbs (9 979 kg)
C-3500 Extended Cab -- 2WD*†
Single Rear Wheels	3.73	15,400 lbs (6 985 kg)	22,000 lbs (9 979 kg)
Dual Rear Wheels	3.73	16,300 lbs (7 393 kg)	23,500 lbs (10 659 kg)
C-3500 Crew Cab -- 2WD*†
Single Rear Wheels	3.73	15,100 lbs (6 849 kg)	22,000 lbs (9 979 kg)
Dual Rear Wheels	3.73	16,200 lbs (7 348 kg)	23,500 lbs (10 659 kg)
K-3500 Regular Cab -- 4WD*†
Single Rear Wheels	3.73	15,400 lbs (6 985 kg)	22,000 lbs (9 979 kg)
Dual Rear Wheels	3.73	16,500 lbs (7 484 kg)	23,500 lbs (10 659 kg)
K-3500 Extended Cab -- 4WD*†
Single Rear Wheels	3.73	14,900 lbs (6 758 kg)	22,000 lbs (9 979 kg)
Dual Rear Wheels	3.73	16,100 lbs (7 303 kg)	23,500 lbs (10 659 kg)
K-3500 Crew Cab -- 4WD*†
Single Rear Wheels	3.73	14,800 lbs (6 713 kg)	22,000 lbs (9 979 kg)
Dual Rear Wheels	3.73	15,900 lbs (7 212 kg)	23,500 lbs (10 659 kg)
Vans
G2500 Cargo Van Short Wheelbase -- 2WD	3.73	10,000 lbs (4 536 kg)	17,000 lbs (7 711 kg)
G2500 Cargo Van Long Wheelbase -- 2WD	3.73	10,000 lbs (4 536 kg)	17,000 lbs (7 711 kg)
G3500 Cargo Van Short Wheelbase -- 2WD	3.73	10,000 lbs (4 536 kg)	17,000 lbs (7 711 kg)
G3500 Cargo Van Long Wheelbase -- 2WD	3.73	10,000 lbs (4 536 kg)	18,500 lbs (8 391 kg)
G3500 Passenger Van Short Wheelbase -- 2WD	3.73	9,900 lbs (4 491 kg)	17,000 lbs (7 711 kg)
*Fifth-wheel or gooseneck kingpin weight should be 15 percent to 25 percent of trailer weight up to 3,500 lbs (1 587 kg) maximum. **The Gross Combination Weight Rating (GCWR) is the total allowable weight of the completely loaded vehicle and trailer including any passengers, cargo, equipment and conversions. The GCWR for the vehicle should not be exceeded. †Trailer rating limited to 13,000 lbs (5 897 kg) with weight distributing hitch.

See "Towing a Trailer" in the Index of the vehicle's owner manual for more information.