Dodge Charger Grilles
But wiring a trailer may not be easy. If you're towing just for the day and don't ever plan to tow again, you can pick up some adapters that replace the taillight bulbs in your vehicle and have pigtailed wires hanging from them. How you route the wires out of the light sockets and down to the hitch can be problematic. And what if you have a trailer with simple 1-lamp lights and a car with multiple taillights, like most European cars? At the very least, odds are the trailer and vehicle use different connectors, as the trailering industry uses at least four different styles.
Red To Green To White
Let's start with the basics. Most trailers have three circuits--for running lights, and left and right brake lights. The brake lights will flash for the turn-signal function--it's up to the flasher relay in the car to know when the brake lights are on and to flash the appropriate filament. So technically, you need only three wires to the trailer plus a ground wire.
Always run a ground wire from the frame of the vehicle (not from the hitch or bumper) to the trailer. The metal-to-metal contact in the hitch is not reliable enough for a consistent connection.
This means you'll need a connector with at least four contacts. Not surprisingly, the standard flat-style connector for trailers uses four pins, with one unshrouded male pin on the vehicle end for the ground. Other common styles of connectors use five, six or seven pins, and these are the styles you'll see installed by the manufacturers on new vehicles. Why more than four? Larger trailers sometimes use a separate circuit for running lights on the sides and front of the trailer. Some trailers use electrically actuated brakes. It's not uncommon for enclosed trailers to have interior lights or accessories powered by the vehicle battery, so that means another circuit.
Do not freak. As long as you concern yourself with only one circuit at a time, this job will not require you to read those schematic diagrams that have tiny little wires labeled with type too small for even a lawyer to read.
Over-The-Counter
Got a 7-pin connector on the truck and an inline 4-pin connector on the trailer? We found an adapter at the auto parts store that makes this plug-and-play. Other permutations of connectors may be adaptable with off-the-shelf parts.
Splice It
Worst case--you have a car or truck with no provision for trailer lights, and a trailer with a harness that ends with chopped-off wires. You'll need nothing more complicated than a 12-volt test light or volt-meter, and some splicing capability. Start by turning on the vehicle's running lamps. Now probe the vehicle wiring to find out which wire leading to the taillights is hot. Splice into this wire and bring it to the vehicle side of the trailer connector. Which pin? The connector should come with a list specifying which pin handles which circuit. Follow it--but don't for a minute trust that someone else who wired your vehicle before you followed anything except his own whim. Tag each wire with its function as you identify it. Now you can turn off the running lamps and activate the left turn signal. Identify which circuit is the blinker, and repeat for the right turn signal. Wire all to the connector.
Dodge Charger Grilles
