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Parts Needed to Re-Wire Car Hauler Trailer Lights and Brakes  


I have an older car hauler type trailer. I believe it was converted from some other kind of use. Maybe a mobile home or something as it has some heavy duty 3inch square tubing for the frame. The wiring on it is kind of a mess and Id like to rewire the entire trailer. It has dual axles but I believe brakes are only on one set. What I could use some help with is getting some good parts for this thing so I can wire it correctly and not have to worry about issues down the road. Ive watched a few videos on your site so I have a much better view then I did before I found your site. And from watching these videos I believe I will need the following: Junction box which one Wiring from front of trailer to junction box which one wiring from junction box to brakes which type? wiring from junction box to lights which type? Also, could use a recommendation for rear brake lights. Is there anything else I need? Thanks.


Expert Reply:

We can help you with selecting parts to re-wire your trailer's lights and brakes.

Trailer size affects the number and types of lights required to be DOT-compliant. I linked for you an article that covers the lighting requirements for trailers of various sizes. This will help you determine what is required for your specific trailer.

For lighting you might want to consider one of our complete lighting kits. Kit # TL29BK uses standard incandescent light bulbs and kit # TLL9RK uses high-efficiency LED type lights. Both work for trailers that are under 80-inches wide. All trailer lights are shown on the linked page. Click on the filters to narrow the results displayed.

You can use a wiring junction box like # 38656 to make the connections from the lights and brakes. You can choose a 7-way trailer plug like 4-foot # H20043, 6-foot # H20044 or 8-foot # H20046. Make sure you match up the wiring by function, not by color. Wire colors are not a reliable method for re-wiring. You'll want to use a tester like # PTW2993 to test any wires whose function is not known.

You'll also need ring terminals to make all the necessary connections within the junction box for lights and brakes. Match up your ring terminals by wire gauge, which varies even within one harness. For 10-12-gauge wires use # DW05741-1; for 14-16-gauge wires use # DW05702-1.

Your electric drum brakes will need 10-gauge wire # 10-1-1 for connection to the junction box. Note that either brake wire can be used for grounding to the trailer frame; brakes are non-polarized so you can use either wire for ground and power. You can use butt connectors # 05732-2 for the 10-gauge brake circuit wire.

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