Tips for Trailering
What is the difference between different wiring harness types?
There are 2 main types of connectors used to connect a trailer’s lights to your vehicle, commonly referred to as the trailer’s “Wiring Harness”.
The first is the flat 4-pin connector. This is the most basic type of connector, and is typically used with smaller trailers that have simple needs. It provides connections only for left and right turn signals, brakes, and running lights.
The second common type is the 7-pin round or RV plug. This plug adds connections for Auxiliary power, reverse lights (in some cases), and control for electric brakes, (more on electric brakes below)
It is important to note that while it is possible to use an adaptor to plug a trailer with a 4-pin connector into a vehicle that only has a 7-pin connector, it is not possible to connect a 7-pin trailer connector to a vehicle that only has a 4-pin plug.
Most newer vehicles have 4 and 7-pin connectors, although many older vehicles only have a 4-pin connector.
Check out this demonstration of the importance of load balancing when towing a trailer.
Importance of loading a trailer correctly
It is very important to make sure that a trailer is loaded correctly before towing. There are 3 main things that should be considered before every time you tow.
Weight Limits - Every trailer is rated for a certain weight. The most common number is labelled as the GVWR, or Gross Vehicle Weight Rating. This is the total allowable weight of the trailer, and it’s cargo. Exceeding this weight puts excessive stress on the tires, axles and frame of the trailer, and in certain circumstances can be illegal.
Load Balancing - Besides not overloading a trailer, it is also very important to ensure that the trailer’s cargo is positioned so that the bulk of the weight is distributed with about 60% of the cargo weight in front of the trailer axle(s). Too much weight in the back of the trailer can contribute to dangerous trailer sway, and can also cause the trailer hitch to get disconnected while on the road. Too much weight in the front of the trailer puts excessive load on the vehicle’s hitch, which can damage the hitch. It can also shift weight away from the front wheels of the towing vehicle, affecting steering and handling.
Securing your Load - As much as the other two considerations, it is very important that your load is appropriately secured. In an enclosed cargo trailer, while you don’t necessarily need to tie down every object in the trailer, it is important to ensure that the load doesn’t move while you’re driving to prevent damage to the cargo, and ensure that the load balance doesn’t shift into a more dangerous orientation. In an open trailer, all loads must be secured. Larger items must be tied down, and loose loads, (like dirt, gravel, or loose garbage), need to be covered to ensure that nothing comes out of the trailer on the road.
Trailer Brakes
Most medium to large sized trailers have some type of braking system required by law. These trailer brakes help to take some of the braking load off of the tow vehicle, and help with handling when slowing down. The two most common types of trailer brakes, are Electric Brakes, and Surge Brakes. Surge brakes use the weight of the trailer pushing against the trailer hitch to activate a hydraulic braking system, and don’t require any special equipment to work. Electric Brakes are more common, and are activated by an electronic brake controller in the tow vehicle. Operating a heavy trailer without using trailer brakes puts additional strain on the tow vehicle, makes slowing and stopping more difficult, and often dangerous.
Trailer Hookup Checklist
Hooking up a trailer isn’t hard, but there’s a few details that need to be checked every time.
Hitch Coupler - Before connecting the trailer, ensure that you have the correct sized hitch ball on your vehicle. Once the trailer is sitting on the ball of the trailer hitch make sure that the latch is closed, and the safety pin is inserted. This ensures that the hitch doesn’t come unlatched from the tow vehicle.
Safety Chains - Connect the safety chains between the trailer and the tow vehicle. The chains should be crossed under the hitch, and should not be hanging too low or dragging on the ground. If the chains are hanging down too low a common trick is to twist the chains to shorten them up a bit.
Lights - The trailer lights should be checked every time a trailer gets connected. Ensure that all running lights, brake lights, turn signals, and marker lights are working properly.
As the driver it is always important for you to take responsibility for the connections of the trailer you are about to tow. You should personally inspect the connections before every time you tow, even if the trailer hasn’t been disconnected and you don’t think anything could have changed.
More Information
There’s lots more to know about towing and trailers, and we’d love to help you answer any other questions that you have. Please feel free to call or email to talk to one of our trailer specialists if you have any additional questions.
For even more information, check out the Ontaio MTO trailer handbook page at https://www.ontario.ca/document/official-mto-drivers-handbook/towing