All About Vehicle Wiring
(written by Sue Monroe)
Wiring A Vehicle - Many newer vehicles have wiring for towing directly from the factory. However, some don’t and then you will have to add wiring to your vehicle. In most places it is the law to have lights on your trailer during the day as well as at night. Today’s vehicles have complex wiring systems and there are T-connectors that are available for easier installation. Some vehicles require converters or power converters. It is best to have experts install your wiring because some vehicles have low amperage systems. You must also determine if you have a 2-wire system or a 3-wire system, and some multiplexed vehicles are not to be cut or spliced into. So, it is better to have it installed professionally.
What type of wiring you will need depends on what you are towing. Some smaller trailers require only a 4 way wire plug which is for stop, turn and taillights. There is also a 5-way wire connector, which will enable to trigger surge brake lock out automatically when backing up or back up lights. This is especially common on boat trailers and is getting more popular. Larger trailers require a brake controller. A brake controller is a device that is installed in your tow vehicle and an electronic signal is sent to the trailer telling it to put the brakes on. This type of connector will require a 6-way or 7 -way plug. The main purpose is to have the trailer stop at the same time that your vehicle does. There are many different kinds of brake controllers on the market, depending on the trailer weight and axles.
A 2-way wire system uses the same wire and bulb to illuminate both the brake light and turn signal. It can be easily identified by the use of a single bulb on each side of the vehicle to light up the brake and turn signal. A 2-way system will generally have red turn and brake light lenses.
A 3-way light systems have separate wires for the brake and turn signal bulb. They have 2 bulbs on each side, one for the brake lights and a separate for turn signals. The 3-way system will generally have amber turn signal lenses. On a 3-way wire system, a taillight converter is required.
If your vehicle requires a taillight converter, you now must choose the correct one. Many newer vehicles are only capable of handling the power need of the vehicle itself. Some trailers demand a large amount of power. This is based on the number of lights installed on the trailer. Since electrical current is measured in amps, you must determine the total amperage draw of a trailer, add the number of bulbs of each light and multiply by each bulbs amperage rating. Taillight/Brake bulbs are rated 2.1 amps each and marker lights draw approximately 0.6 amps each.