2004 GMC Sonoma Owner's Manual - Page 240

If you'll be pulling a trailer, that when loaded, 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. You should always use a sway control if your traile will weigh more than these limits. You can ask a hitch dealer about sway controls. Trailer Brakes If your trailer weighs more than 1,000 lbs. (450 kg) loaded, then it needs its own brake-and they must be adequate. Be sure to read and follow the instructions for the trailer brakes so you'll be able to install, adjust and maintain them properly. Your trailer's brake system can tap into the vehicle's hydraulic brake system only if: Safety Chains You should always attach chains between your vehicle and your 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 3,500 lbs. (1 589 kg) you may attach the safety chains 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 you can turn with your rig. Never allow safety chains to drag on the ground. • The trailer parts can withstand 3,000 psi (20 650 kPa) of pressure. • The trailer's brake system will use less than 0.02 cubic inch (0.3 cc) of fluid from your vehicle's master cylinder. Otherwise, both braking systems won't work well. You could even lose your brakes. If everything checks out this far, then make the brake fluid tap at the port on the master cylinder that sends fluid to the rear brakes. But don't use copper tubing for this. If you do, it will bend and finally break off. Use steel brake tubing. Driving with a Trailer Towing a trailer requires a certain amount of experience. Before setting out for the open road, you'll want to get to know your rig. Acquaint yourself with the feel of handling and braking with the added weight of the trailer. 4-60