GM Service Manual Online
For 1990-2009 cars only

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:

    • 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" later in this section.
    • Do not tow a trailer at all during the first 500 miles (800 km) the new vehicle is driven. The engine, axle or other parts could be damaged.
    • Then, during the first 500 miles (800 km) that a trailer is towed, do not drive over 50 mph (80 km/h) 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 with automatic transmissions can tow in D (Drive), but you may want to shift to a lower gear selection if the transmission shifts too often (e.g., under heavy loads and/or hilly conditions). If the vehicle has a manual transmission it is better not to use the highest gear.

Three important considerations have to do with weight:

    • The weight of the trailer
    • The weight of the trailer tongue
    • The weight on the vehicle's tires

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*

2WD Regular Cab

  • 2.9L L4 Automatic Transmission

3.73

3,400 lbs (1 542 kg)

7,000 lbs (3 175 kg)

  • 2.9L L4 Manual Transmission

3.73

2,400 lbs (1 089 kg)

6,000 lbs (2 722 kg)

  • 3.7L L5 Automatic Transmission

3.73

4,000 lbs (1 814 kg)

8,500 lbs (3 856 kg)

2WD Extended Cab

  • 2.9L L4 Automatic Transmission

3.73

3,200 lbs (1 452 kg)

7,000 lbs (3 175 kg)

  • 2.9L L4 Manual Transmission

3.73

2,200 lbs (998 kg)

6,000 lbs (2 722 kg)

  • 3.7L L5 Automatic Transmission

3.73

5,500 lbs (2 495 kg)

9,500 lbs (4 309 kg)

  • 5.3L V8 Automatic Transmission

3.42

3.73

6,000 lbs (2 722 kg)

10,400 lbs (4 717 kg)

  • 5.3L V8 Automatic Transmission, ZQ8 Sport Suspension

3.42

4,000 lbs (1 814 kg)

8,500 lbs (3 856 kg)

2WD Crew Cab

  • 2.9L L4 Automatic Transmission

3.73

3,000 lbs (1 361 kg)

7,000 lbs (3 175 kg)

  • 2.9L L4 Manual Transmission

3.73

2,100 lbs (953 kg)

6,000 lbs (2 722 kg)

  • 3.7L L5 Automatic Transmission

3.73

5,500 lbs (2 495 kg)

9,500 lbs (4 309 kg)

  • 5.3L V8 Automatic Transmission

3.42

3.73

6,000 lbs (2 722 kg)

10,400 lbs (4 717 kg)

  • 5.3L V8 Automatic Transmission, ZQ8 Sport Suspension

3.42

3,800 lbs (1 724 kg)

8,500 lbs (3 856 kg)

4WD Regular Cab

  • 2.9L L4 Automatic Transmission

3.73

3,100 lbs (1 406 kg)

7,000 lbs (3 175 kg)

  • 2.9L L4 Manual Transmission

3.73

2,100 lbs (953 kg)

6,000 lbs (2 722 kg)

  • 3.7L L5 Automatic Transmission

3.73

4,000 lbs (1 814 kg)

9,000 lbs (4 082 kg)

4WD Extended Cab

  • 2.9L L4 Automatic Transmission

3.73

2,900 lbs (1 315 kg)

7,000 lbs (3 175 kg)

  • 2.9L L4 Manual Transmission

3.73

1,900 lbs (861 kg)

6,000 lbs (2 722 kg)

  • 3.7L L5 Automatic Transmission

3.73

5,500 lbs (2 495 kg)

9,800 lbs (4 445 kg)

  • 5.3L V8 Automatic Transmission

3.42

4.10

6,000 lbs (2 722 kg)

10,400 lbs (4 717 kg)

4WD Crew Cab

  • 3.7L L5 Automatic Transmission

3.73

5,500 lbs (2 495 kg)

9,800 lbs (4 445 kg)

  • 5.3L V8 Automatic Transmission

3.42

4.10

6,000 lbs (2 722 kg)

10,400 lbs (4 717 kg)

*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.

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.


Object Number: 806596  Size: B2

The trailer tongue weight (A) should be 10 percent to 15 percent of the total loaded trailer weight, up to a maximum of 500 lbs (226 kg) with a weight carrying 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:


Object Number: 1589847  Size: B1

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:


Object Number: 1589848  Size: B1

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/Tire label located at the bottom of the center pillar on the driver's side of the vehicle, 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 step bumper hitch can be used for trailers up to 2,000 lbs (907 kg) total weight, and 200 lbs (90 kg) tongue weight.

Notice: If a step-bumper hitch is 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.

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. Instructions about safety chains may be provided by the hitch manufacturer or by the trailer manufacturer. For trailers up to 2,000 lbs (907 kg) safety chains may be attached to the attaching points on the bumper. For heavier trailers, follow the trailer or hitch manufacturer's recommendation for attaching safety chains. Always leave just enough slack so the rig can turn. Never allow safety chains to drag on the ground.

Trailer Brakes

A loaded trailer that weighs more than 1,000 lbs (450 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.

Since the vehicle is equipped with StabiliTrak®, the trailer cannot tap into the vehicle's hydraulic brake system.

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.

While towing a trailer or when exposed to long periods of sunshine, the floor of the truck bed may become very warm. Avoid putting items in the truck bed that might be affected by high ambient temperatures.

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.

Vehicles with automatic transmissions can tow in D (Drive), but you may want to shift to a lower gear selection if the transmission shifts too often (e.g., under heavy loads and/or hilly conditions). If the vehicle has a manual transmission it is better not to use the highest gear.

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 an automatic transmission in P (Park) or a manual transmission in N (Neutral) with the parking brake applied, 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 into P (Park) yet for vehicles with an automatic transmission, or into gear for vehicles with a manual transmission. 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) for vehicles with an automatic transmission or into gear for vehicles with a manual transmission.
  5. If the vehicle has four-wheel-drive, be sure the transfer case is in a drive gear and not in N (Neutral). See Four-Wheel Drive for more information.
  6. Release the brake pedal.

Leaving After Parking on a Hill

  1. Apply and hold the brake pedal while you:
  2. • Start the engine
    • Shift into a gear
    • Release the parking brake
  3. Let up on the brake pedal.
  4. Drive slowly until the trailer is clear of the chocks.
  5. 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 Scheduled Maintenance or the 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 vehicle may be equipped with a four-pin trailer towing harness. This harness has a four-pin trailer connector that is attached to a bracket on the hitch platform. The four-wire harness contains the following trailer circuits:

    • Yellow: Left Stop/Turn Signal
    • Green: Right Stop/Turn Signal
    • Brown: Taillamps/Park lamps
    • White: Ground