Trailer Wiring from Scratch Using Hopkins 7-Way Part H20046
Updated 02/17/2010 | Published 02/15/2010
Question:
Hi I am adding some lights and replacing some wire to a equipment trailer I just bought and I had some questions about it. My first question is am adding marker lights and there is only one wire coming out of the new marker lights I bought so I would connect the brown wire to the wire that is coming out of the marker light? My second question is what is the black, 12 volt hot wire, used for and what is it purpose and where should I connect it to? My third question has to do with brake lights. I bought a plug and wire already made up from you. Its the 7 way plug with 6 wire. I looked at your diagram for wire set-up on the plug and it says Red - left turn/brake and Brown-right turn/brake. So my question is all I have to do is just hook up each wire with their respectable sides and that one wire wire will take care of both the turn signal and the brake lights correct? And my fourth and final question is on that plug it says yellow-aux does is this for back up lights if the trailer has them and or hydrallic brakes? If not what wire color on the plug works for back up lights and hydrallic brakes. Thanks
asked by: Kevin R
Expert Reply:
Since your side marker lights have only one wire coming out, that means they are grounded via the screws, bolts or studs they use for mounting. The wire should be attached to the tail light circuit, typically the brown wire.
The 12V black wire on a vehicle is used as a power source for something on the trailer. It connects directly from the vehicle battery, usually with a 40 amp circuit breaker. Some trailers have a hydraulic lift and the 12V circuit would power the pump. It could also be used to charge a trolling motor battery on a fishing boat. If you do not need a power source on your trailer it can be omitted.
I checked your sales record and it shows you ordered part # H20046, a 7-Way trailer connector with 8 feet of wire leads. It should have 7 wires: white, red, brown, green, blue, black and yellow. Hopkins did not follow standard wiring colors for this part so you will need to use the car to identify which wires serve what function. As you mentioned the red wire is left turn/brake and the brown wire is right turn/brake. Yes, the brake and turn signal functions are sent on the same wire. The green wire from the 7-way should be run back to the side markers and tail lights that come on with the truck headlights. Follow the chart on the H20046 page and run the wires to the lights.
The yellow wire, auxiliary circuit, is the center pin on the connector. It is typically used for reverse lights. If you have hydraulic brakes on your trailer, this circuit is used to activate the reverse lock-out if your trailer brake system has a reverse lock out. If your trailer has electric brakes, you would use the blue wire for the brake magnets.
Always double check your wiring using a circuit tester, like part # PTW2993. Have a label maker or some masking tape with a marker to label the wires so you do not mix them up while wiring. I have added a link to a wiring help page that should be useful. Remember, in some cases manufacturers do not follow the standard wiring color code for trailers. The Hopkins part you have is one of those parts.
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