before I wind up tearing it apart, I thought I should ask.

How do you get constant 12V out of the #4 (black) prong on the 7 wire plug? Is there a setting I need to change, or a fuse I need to add, or is it not wired to anything? I want to have a 12V constant to run the lights & charge the battery in my racing trailer.

Thanks guys.

 

The aux wire is only hot when the key is on.

 

Doh! I shoulda thought of that!

 

Tried it, still didn't work... Any ideas?

 

 

You should be able to use the aux also for a constant 12v source too. Use a voltage meter or test light to find what has voltage and what doesn't. If you can find voltage at the conection at all, then start looking for a blown fuse or bad relay.