How to Wire Boat Trailer Lights to a Car
Trailers, just like cars and trucks, are required to have working taillights, brake lights and turn signal lights if you want to tow them on public roads. Some trucks and SUVs come from the factory with prewired receptacles into which a trailer light plug can be attached. Most cars don't come with prewired receptacles, however. But installing one is certainly possible.
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Things You'll Need
- 4-wire trailer receptacle
- 4 blue dual-port connectors
- 1 ring tongue solderless connector
- Electric drill
- Self tapping metal screw
- 12V test light
- Helper
- Pliers
- Electrical tape
Instructions
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LOCATE CAR WIRES
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1
Crawl under the rear of your vehicle and locate the rear light wiring harness. The harness is usually bundled in a corrugated plastic conduit split lengthwise, which can be spread to expose the wires within.
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2
Attach the ground clip on the 12V test light to a bare metal part of the car's body or frame.
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3
Determine which wire inside the harness goes to which light or lights. Pick a wire. Penetrate the insulation on the wire with the sharp pointed end of the 12V test light. Have a helper turn the vehicle's key to the run position without starting the engine, then turn on the headlights. If the test light glows when the headlights are switched on, you've found the taillight wire. Mark it so you can remember its color. If the test light doesn't turn on, have the helper turn on one or the other turn signal. If the test light blinks on and off with either turn signal, you've found one of the turn signal wires. Repeat the test on the other wires in the harness to find the other turn light wire.
Connect The Wires
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4
Install a dual port connector on each wire (right turn, left turn and tail light). Dual port connectors have one side open, which will allow putting them on a solid wire.
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5
Put one of the colored wires on the trailer receptacle into the other hole in the dual port connector. The green wire connects with the right turn signal wire. The yellow wire pairs with the left turn signal wire and the brown wire hooks to the taillight wire. Once both wires are in the splicer, pinch the metal part down on the splice and fasten the plastic clip into the locked position.
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6
Drill a hole through a metal part under the vehicle, put a ring tongue connector on the end of the ground wire (white) on the trailer receptacle and attach the ground to the hole you just drilled with a self tapping screw.
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7
Use electrical tape to wrap everything tight and tidy.
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1
Tips & Warnings
Test the connections by turning the key to run and have your helper turn on the car's lights, activate the turn signals and step on the brake while you are inserting the tip of the test light into the appropriate sockets on the plug.
