I cant remember who told me this fix but here it is. I just now got around to making this repair and wanted to share it with you all who may have the same problem. I'm not sure if all 07 150's have this but I know both of mine did!
The manufacture wired the atv wire harness up different then the tail light. So when you hook the tail light up the brake light will not light up when the head light is on. Actually I don't remember if the Brake light worked at all.
As you can see the Green and the Brown wires needs to be switched, I did the switch at the connector on the tail light side! Now all works perfect!
Here are photos of my fix!

 

Actually, you don't have to even cut the wires.
Separate the white plastic wire connector.
Looking into the end of the now exposed 'tail light connector' (male plastic end); take a 'bobby pin' with the plastic protection end scraped off, and slide it into the connector and 'depress' the little metal 'tang' that is on the metal wire connector. The wire with the 'wire connector end', slides right out of the white plastic housing.
Do this for both wires - swap locations and reinsert the 'wire end connectors' in the correct positions within the white plastic housing.
Time to fix, approximately 90 seconds.

 

That would be better, last time I tried it I ended destroying the plug so I opted for the wire cut!