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Troubleshoot Wiring 4-Way to 7-Way Wiring of Trailer  


Expert Reply: If you do not plan on using the brakes of your trailer you can splice a 4-way into the 7-way wiring so that you could control the taillights of the trailer. For that you could use the part # HM48110 to wire in the 4-way. Or you could just use a 7-way to 4-way adapter on the trailer like the part # 30717 and just tape up the extra wires that wouldnt be used. expert reply by: Jameson C I have purchased and received the above part, tried it on car and trailer, but nothing on trailer is working, is it POSSIBLE THE ABOVE PART IS NOT WIRED IDENTICAL TO 4 PIN FOR LIGHTS ON TRAILER? I put volt meter on car plug and got movement at each pin when using blinker and lights. *Trailer is a Little Guy camper with no battery so charge line not needed, and no trailer brakes and a 7 pin connector, which worked on previous car with a 7 pin connector on it *car i just purchased is a used 2013 Subaru Outback with Hitch and a 4 pin connector Any input would be appreciated Thanks


Expert Reply:

If you wired the part # HM48110 to the correct circuits of your trailer it should operate the trailer lights. Since you said the trailer worked just fine on a different vehicle with a 7-way the problem has to be that you attached the 4-way to the wrong circuits of the trailer.

You will want to use the 7-way diagram I attached as a guide so that you can know the proper functions of each of the wires of your 7-way so that you can wire them to your trailer correctly.

You should also verify that the 4-way of your vehicle is functioning properly by testing it with a circuit tester like part # PTW2993.

expert reply by:
Jameson C
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