Transmission Upgrades

• Towing a trailer puts strain on a vehicle's transmission. Towing packages always include an additional transmission cooler. A transmission cooler includes a heat exchanger near the radiator and piping to connect the transmission to the heat exchanger, as well as additional transmission fluid for the piping and the heat exchanger. The heat exchanger keeps the transmission fluid from overheating and breaking down. Some towing packages include a different transmission program that will change the timing of gear changes to make driving with a trailer easier. A dash-mounted switch accesses the towing program, or it may come on automatically when the vehicle senses a trailer.
  
  

Electrical Upgrades

• The towing vehicle controls the lights on the trailer. Marker lights, brake lights, turn signals and license plate lights for trailers are required to work, just as they are for the towing vehicle. A four-pin wiring harness -- which is enough for a lightweight trailer -- is adequate to control the lights on a trailer. Heavier trailers also have brakes controlled by the towing vehicle. A seven-pin wiring harness is included in a heavy-duty towing package to enable the towing vehicle to control the trailer's brakes.
  
  

Suspension Upgrades

• Hitching a trailer to a vehicle shifts the towing vehicle's center of gravity towards the back, which can cause handling issues for the driver. A heavy-duty towing package includes a load-distributing hitch, which carries some of the tongue weight of the trailer to the front suspension of the towing vehicle. A heavy-duty suspension will be stiff when driving the vehicle without towing a trailer.
  
  

What is Included?

• A well-informed purchaser will confirm with the dealer exactly what is included in any towing package and how that will influence the vehicle's towing ability. A vehicle that tows a small travel trailer does not have the same needs as a vehicle that tows a large boat. It is also important to be aware that some upgrades for towing will negatively affect driving when the vehicle is not towing anything. For example, a heavier suspension will make the ride harsh when the vehicle is without a trailer, and a higher differential ratio increases maximum payload but may decrease fuel economy.