How to Wire Trailer Lights

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By Gerrie Grimsley
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Wire Trailer Lights

If you are considering towing a trailer or camper behind your car, truck, or RV this year, you might save yourself a possible headache, lawsuite, or worse, by making sure your trailer lights are wired and working correctly.

Difficulty: Moderate

Instructions

Things You'll Need:

12 Volt Test Light
Trailer Light Connector
Electrical Tape

Step 1

12 volt test light w/clip

GET IT ALL TOGETHER
Providing your trailer is either factory or custom built, wiring your vehicle for trailer lights is easy and should only take a few minutes if you have all the items you need at your side before you begin.
Step 2

4-wire flat connectors

KNOW YOUR STYLE
Most cars are already equipped with one of two different styles of
4-wire/pins quick connect receptacles which are normally used and cover basic tail and blinker lighting. These are quick and easy to use and the two different styles are compatible with each other.

Note: If your trailer has a 5-wire (or more) connecting receptacle, you will need to purchase a "trailer light converter" that can be found at any Auto Parts Store. You can get a kit with everything you need. In this case you will follow the instructions on your converter kit.
Step 3

Click on the diagram if you need to read the details

KNOW THE COLOR CODES FOR CORRECT FITTING
The wires on either type of receptacle will be color coded and it is important to know the code. The colors are white, yellow, green and brown. This the most common wiring code:

Brown wire to the tail or parking lights
Green wire to right turn signal
Yellow wire to the left turn signal
White wire to common or chassis ground
Step 4

NOW, LET'S DO THE WORK
FIRST - Locate your vehicle's taillight wiring harness. (This is normally found in the trunk or around the rear bumper.)

SECOND - Locate a spot for your hook up place. Make sure the wiring harness is long enough to reach your trailer' s connector receptacle. If it is not long enough, you will have to purchase more wire or an additional connector at your local auto parts store.

THIRD - Use the clip end of your "test light" and clean off a small area of metal on the car frame (called the "chassis.") to use as your ground. Then turn the headlight switch so that the parking light is "on".

Using the test light, probe the wires until it lights up. If it comes on and stays on, you are ready to connect the brown wire to that wire with a quick connector. Your tail, or parking lights, should be ready to go if all has worked out well with this step!

Now turn your headlights off.

FOURTH - Turn your ignition on and start the right turn signal working. Using the test connector once again and repeat the process of probing the test light until it comes on and stays on.

This is the wire that will be the right turn signal and right brake light wire. Now connect the yellow wire to this wire. Turn ignition off now and prepare for the next step.

FIFTH - Turn the ignition switch on again and keep it in the "run" position and activate the left turn signal. Once again, probe the wires with the test light until the light flashes. This wire will be the left turn signal and left brake light wire. Connect the green wire to this wire. Turn off the ignition.

SIXTH - The last wire to connect is the white wire. If you have an existing ground wire, attach this white wire to your ground wire.

If you do not already have a ground wire to attach the white wire to, clean off an area of metal chassis for your ground and you will have to connect the white wire using sheet metal screw.

Now your installation is complete.