Electric trailer factory harness

I have just hooked up my harness supplied by toyota with the truck, to a brake controller but the green wire off the factory harness is for the headlight switch. I left loose, not sure where to connect it to. As a result when I turn the head lights on I have no trailer running lights. I do have running lights though on the running light switch. But not when I turn the head lights. I suspect I should attach that wire brake signal wire on my controller?

 

Strangest thing works now. And it is called an illumination wire. I did find out from the dealer you have to keep it loose when installing aftermarket controllers