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Why Does Trailer Wiring for a 2011 Ford E-350 Van Require a Converter and Power Wire


What is the purpose for the power module on the tow ready part # 118551 ? I have a 2011 ford e 350 with out the factory towing package. On my older vans we just wired the trailer wires to the back of the tailights.


Expert Reply:

Vehicle tail light wiring has changed quite a bit over the past few years. There are basically 2 wire systems and 3 wire systems. A 2 wire system has combined brake lights and turn signals. A 3 wire system has separate turn signals and brake lights. Three wire systems require a converter to change the signal over to a 2 wire system which is what a trailer uses.

Also, on some vehicles it has been determined that the electrical system cannot or should not handle the load from its own tail lights and the trailer lights as well so they need a powered converter. These converters get power for the trailer lights primarily from the vehicle battery. This protects the vehicle electronics.

There are even more complicated systems that use various pulses on one wire for all functions and others that use various constant voltage on 1 or 2 wires for all the functions. More and more vehicles require a converter these days.

T-connectors like # 118551 for the Ford Van are fairly easy to install. I have linked the instructions for you and a video showing a typical installation.

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