Just got done hooking up my new (to me) Tag a Long Wheel-less trailer harness to my Roadsmith conversion. First issue I had was that when I connected the red fused lead to the positive battery terminal on my GL1500 I got NO POWER. After I dropped the bottom part of my top trunk, I noticed that one of the two connectors that plug into the lights in the trunk had come undone and when plugged back in, the harness worked like a champ. The harness was sourced from a company called AddOn Accessories. A red wire runs into a bank of relays that in turn plug into the original lights/signals. The diagram for connecting a trailer to your Roadsmith is in the Installation Manual or Owners manual and I found it to be incomprehensible (others may not find it so!).

The colors out of the AddOn Accessories harness on a Roadsmith are:

Green = ground
Brown = tail/running light
Yellow = brake light
Orange = left turn signal
Blue = right turn signal

The Roadsmith wiring diagram is included:

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Hope this helps someone out there who runs into wiring his trailer to his Roadsmith conversion!