Making Trailer Wiring Adapter for Semi Truck Towing Trailer with RV Blade Style 7-Way  

Question:

Expert Reply:

If you need to keep the 7-Way semi active on the truck, then you would need to make an adapter to get it to work with an RV 7-Way. For that you would need a trailer side 7-Way round, # PK11702, a converter, # RM-732, and a vehicle side 7-Way RV style, # PK12-707E.

A semi-7-Way has separate circuits for the brake lights and each turn signal. And RV style 7-Way has the brake lights combined on the same circuit. So, what you would do is use a circuit tester such as # PTW2993 to determine the functions of the 7-Way on the tow vehicle. Then you would place the red wire from the converter to the appropriate spot on the back of the trailer side 7-Way round for brake lights. Do the same with the green wire for right turn signal and the yellow wire for left turn signal.

You will also need additional wire to attach to the back of the 7-Way round for the other functions needed. For ground and 12-volt power you can use # 10-2-1. For running lights, you can use # 16-1-1, and for electric trailer brakes use # 10-1-1.

On the output side of the converter, you will attach the wires to the back of the vehicle side RV 7-Way. The green wire will attach at the 9 o'clock position, yellow goes to the 3 o'clock position. Ground goes to the 5 o'clock position, 12-volt power goes to 11 o'clock position. Running lights goes to the 1 o'clock position. The center pin is for reverse lights which is uncommon on many trailers. But if needed you will attach some wire to the appropriate pin on the 7-Way round pin and attach it to the center pin on the back of the RV style 7-Way.

expert reply by: Jameson C

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