2003 Mercedes ML-Class Owner's Manual - Page 194

Operation Driving instructions Attaching a trailer Observe maximum permitted trailer dimensions (width and length). Most states and all Canadian provinces require safety chains between your tow vehicle and the trailer. The chains should be crisscrossed under the trailer tongue. They must be attached to the hitch receiver, and not to the vehicle's bumper or axle. Be sure to leave enough slack in the chains to permit turning corners. a separate brake system at various trailer weights. a break-away switch on trailers with a separate brake system. The switch activates the trailer brakes in the possible event that the trailer might separate from the tow vehicle. ! Do not connect a trailer brake system (if trailer is so equipped) directly to the vehicle's hydraulic brake system, as your vehicle is equipped with antilock brakes. If you do, neither the vehicle's brakes nor the trailer's brakes will function properly. Towing a trailer There are many different laws, including speed limit restrictions, having to do with trailer towing. Make sure that your rig will be legal, not only for where you reside, but also for where you will be driving. A good source for this information can be the police or local authorities. Note the following points, when driving with the trailer: In order to gain skill and an understanding of the vehicle's behavior, you should practice turning, stopping and backing up in an area which is free from traffic. Before you start driving check the trailer hitch break-away switch safety chains electrical connections lighting and tires i The provided vehicle electrical wiring harness for trailer towing has a brake signal wire (color orange) for hook-up to a brake controller. You should consider using a trailer sway control system. For further information see your authorized Mercedes-Benz Light Truck Center. 194