Unless you are building the trailer lighting system, you have to use the converter.  American rear lights use one filament for both the turn signal and the brake light.  European lighting uses a separate filament (2 bulbs)

You need the box for the turn signals to work.

Jim

> On Jul 11, 2015, at 10:28 AM, Spencer Allen <spencervw@AOL.COM> wrote:
> 
> -----Original Message-----
> From: Spencer Allen <spencervw@AOL.COM>
> To: vanagon <vanagon@GERRY.VANAGON.COM>
> Sent: Sat, Jul 11, 2015 12:27 pm
> Subject: help powered trailer converter
> 
> 
> Hi all. I want to wire up a flat 4 plug pig tail for towing a trailer on my 85
> Westy. Should I use a powered converter or just use a non powered plug and
> splice in to the tail/brake turn wires? If I use the powered plug where will the
> heavy red wire splice to? Anyone have a diagram for hooking up a trailer plug in
> an 85 ? I probably can figure it out but don't want to butcher the wiring. Any
> help is appreciated. Thanks.
> Spencer
> 85 Westy