How to Wire a Boat Trailer With LED Lights

How to Guides

Boat trailers and their lights can cause so much frustration for boaties.

Has this ever happened to you? You test your trailer lights before your trip to the boat ramp, and all works fine. Fast forward five hours. You’ve retrieved your boat and are ready to drive home with the catch. You test your trailer lights in the car park and the brake lights aren’t working. Not a glimmer.

So frustrating.

A boat trailer with recently re wired led trailer lights attached and working correctly.


Trailer Wiring – Why the Lights Aren’t Working

There can be a number of reasons why your lights fail.

The obvious one is corrosion - saltwater and wiring don’t mix. Once the wiring is several years old, it can start to corrode, particularly if there are several joins. There may be corrosion where the wiring connects to the lights when you remove the plastic housing. The plug may also have some corrosion or just be dirty and in need of a good clean.  


How to Wire a Trailer with LED Lights – Step by Step

You don’t necessarily need specialised tools to rewire a trailer - your basic home toolbox should let you complete the job without too much hassle.  We have listed some general steps outlining the process below, however you must always strictly follow the manufacturer's instructions that come with the lights you purchase, especially the trailer wiring diagram.

If you are unsure about anything, always seek help from a professional such as a qualified electrician or mechanic.


Step 1 - Secure your Boat Trailer

Attaching the boat trailer to your car’s tow bar will anchor the trailer, so it doesn’t move while you are working around it. You will need to hitch your car to the trailer to test the lights so you may as well do it at the start.


Step 2 - Running the New Wiring

Remove the old lights by unscrewing them, then disconnect the old wires if they need to be replaced. Thread the new wiring through the chassis rail underneath of the trailer. Attach the wires to the trailer frame with cable ties to keep them from hanging down. It’s a legal requirement that the cable is supported at least every 60 cm.


Step 3 - Trim and Strip the Insulation

Trim off any length of excess wiring then use cable strippers to remove about 1 cm of insulation off the ends of all wires.


Step 4 - Mounting the New Lights on the Trailer

Take your lights out of the packaging and find the one that has the number plate light. Attach this to the correct side of the trailer so your number plate is lit at night. Use the same position as the old trailer lights to take advantage of any existing holes. Ensure the lights are equally spaced from the centre line. If there are no holes or they are in the wrong place, drill the holes in the trailer.

Slide the bolts or screws through the trailer before securing the lights. Do the same on the other side.


Step 5 - Wiring Connection

Match each coloured wire on the light to the same colour wire on the trailer and twist firmly. Follow the trailer wiring diagram that should be included with the lights you bought. Generally, the wiring should follow the following colour codes:

  • Left indicator - yellow
  • Right indicator - green
  • Reverse - black
  • Brakes - blue
  • Stop lamps - red
  • Earth return - white
  • Rear lamps: clearance and side markers, brown

Tighten the light housing with enough pressure that it connects with the earth wire (if there is one) but be careful not to crack the plastic housing.


Step 6 - Connecting the Trailer Plug

Take the trailer plug and secure it to your car. It’s also a good idea to apply some TefGel Anti-Seize lubricant to the plug socket to help prevent any corrosion in the future. Attach your car to the trailer tow bar. Don’t make the mistake of thinking you can just plug the trailer into the car, it’s often not enough of an earth. A full electrical earth is required so the car and trailer must be in physical as well as electrical contact.

Ask someone to jump in the car to help check the lights are working. Ask them to test the left indicator, right indicator, brake lights and reverse lights.

Once you are happy everything works fine, slide a piece of heat shrink over the joins and use a heat gun to seal. Repeat for the second light. If you don’t have heat shrink, seal the connections with electrical tape to keep out any moisture.  


How to Maintain the LED Lights and Wiring on Your Boat Trailer

If you have been boating for any length of time, you will know that your trailer and its lights need regular testing and maintenance.

Firstly, you need to check all the lights are working every time you hitch the trailer to your car. The lights & wiring also need regular maintenance. Every six months, take a close look at the wiring, make sure it isn’t cracked, none of the lenses have been damaged and the lamps are working fine. Also, check the reflectors on your trailer are still attached and in working order.

National Requirements for Boat Trailers

The federal Department of Infrastructure, Regional Development and Cities regulates much of Australia’s transport requirements. Their Australian Design Rules (ADR) are national standards for new and second-hand vehicles supplied to the Australian market.

These requirements are based on regulations set by the United Nations Economic Commission for Europe. In 1989 the Australian Government assumed responsibility for the ADR under the Motor Vehicle Standards Act 1989, but before this the individual states and territories were responsible for their own trailer regulations. The ADR section on trailers covers all kinds, including semi trailers, box, tray, car carrying, horse floats, caravan and boat trailers.



What’s Required for Your Trailer Lights?

It’s a legal requirement for your boat trailer to have working lights no matter what time of day or night it’s on the road. Boat trailers are allowed to have detachable lights and wiring from trailers where they may be immersed in water and cause short-circuiting. However, most of the LED trailer lights sold today are fully sealed and watertight for submersion.

Manufacturers of trailer lights are responsible for making sure they comply with Australian standards, but trailer owners must ensure their lights are installed and maintained according to the manufacturer’s instructions.

Lights on trailers must operate with the corresponding lights on the towing vehicle. Lights on a trailer must not show red light to the front or white light at the rear except for the reversing light. The colours allowed for each light position and reflector are listed in the Technical Requirements for trailers.            


Legal Requirements for Electrical Wiring

Electrical wiring on trailers must be supported at 60 cm intervals, and also:

  • be insulated at joints
  • be located where it can’t become overheated
  • not be in contact with any moving parts
  • be protected from chafing, and
  • have an earth return wire between the towing car and trailer.    

If you have any concerns about the wiring on your trailer, contact an auto electrician.

Not all boating mishaps happen on the water. Up to half of all boat insurance claims in Australia are as a result of damage while the boat is on the trailer or in transit. Making sure your lighting meets all the requirements will give other road users the best chance of seeing you and knowing what action you are about to take.


Need to upgrade or repair the lights on your trailer? Check out our selection of LED trailer lights including LED submersible kits, adaptor plugs and sockets to replace the lights on your trailer.

We also sell complete LED Trailer light kits including this box LED kit with 5m cable and this submersible LED light kit with 9m cable.

If you have any queries about your boat trailer, don’t hesitate to call the experts at Boat Accessories Australia on 1300 308 161 or contact us online.



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