How to Wire a Camper with a Plug Diagramby John Cagney Nash
Wiring a camper to tow a trailer is made easier if the camper already has a plug installed and a plug diagram detailing the correct terminal-to-wire connections. Campers are typically wired either with a four- or seven-pin hitch. The four-pin installation will transfer information from the camper to the trailer to operate the trailer's brake, turn and side/tag lights. The seven-pin installation will also operate the trailer's electric brakes, backup lights and keep a 12-volt battery charged. Both installations are made according to an industry standard set of color codes.
Consult the plug terminal location diagram supplied with your camper. If your plug has a case to protect it from the elements use your screwdriver to remove the case, then confirm that the orientation of the terminals corresponds to the industry standard layout. Looking at the plug from behind, for a four-pin hitch that layout should be left-to-right from the back white, brown, yellow then green. For a seven-pin hitch that layout should be clockwise from 12 o'clock as black, green, blue, white, yellow, brown with purple in the middle.
Locate the four- or seven-core connection wire provided to power the plug, and trim an inch of its outer jacket away using a box cutter. Avoid damage to the insulation around the separate wires.
Strip the color-coded insulation away from each separate wire using your wire strippers. Trim off half an inch of insulation. Twist each bared length between your fingers to make separate tight braids that look like rope.
Use your crimping tool to attach a connector to the end of each wire. If the terminals on your plug receive spade connectors, attach spade connectors. If the terminals on your plug use threaded captive bolt connections with washers and nuts, attach a eyelet connector to the end of each wire.
Attach the wiring to the terminals of a four-pin hitch using your plug diagram as follows: Attach the 10-gauge white wire to the vehicle ground terminal at the left. Attach the 14-gauge brown wire to the tail lights/running lights/license plate terminal at second left. Attach the 14-gauge yellow wire to the left turn/brake light terminal at second right. Attach the 14-gauge green wire to the right turn/brake light wire terminal at the right.
Attach the wiring to the terminals of a seven-pin hitch using your plug diagram as follows: Attach the 14-gauge brown wire to the tail lights/running lights/license plate terminal at 1 o'clock. Attach the 14-gauge yellow wire to the left turn/brake light terminal at 3 o'clock. Attach the 10-gauge white wire to the vehicle ground terminal at 5 o'clock. Attach the 12-gauge blue wire to the brake controller terminal at 7 o'clock. Attach the 14-gauge green wire to the right turn/brake light wire terminal at 9 o'clock. Attach the 10-gauge black wire to the chassis battery terminal at 11 o'clock. Attach the 14-gauge purple wire to the back-up lights terminal in the center.
Reinstall the outer case if one is provided, then ask an assistant to watch the trailer light clusters as you test their functions. If using electric brakes, test their function according to the manufacturer's instructions on a flat and level surface where you will not endanger other road users.
Use a voltage meter to confirm the 12-volt feed is properly powering the battery charge circuit. Set the meter to measure 12 volts according to the manufacturer's literature, and then measure between the battery charge terminal and a ground connection. The reading should approach 14 volts with the engine of the tow vehicle running.
Items you will need
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