Towing Wire Harness: Aux. Battery not Charging

I just got a travel trailer and am towing it with my 2002 Bravada (TB twin). However, when I tested the marine battery to see if it was getting juice from the wire harness with the engine on; I got nothing.

Then I hooked up my volt meter to the negative and to the "power" pin on the built-in wire harness to see if there was any juice and got nothing. To my knowledge, I should get at least 12 volts when the engine is running to charge the marine battery on the RV when towing.

I checked all my fuses and everything is good there.

Does anyone have any ideas why It's not charging the RV battery when the engine is on (or why there's no juice flowwing thru?).

OK, I solved the problem.

The fuse block has an empty ring terminal on it next to the fuse designated for the trailer 12V lead. I thought that maybe that where you hook up a wire to it. I was ready to make my own when I noticed a suspicious bright red wire bulging out of a plastic wire harness. I pulled a little and voila! ...a little ring for a ring terminal was magically connected to its loose end. AND it was exactly the right size for that ring terminal I had just discovered.

After testing everything with my voltmeter, it's a done deal!

One note: The trailer battery will always be charging since the juice is ALWAYS on. So just unplug the wire harness when you are finished towing or you'll drain your TV battery (or maybe they'd equalize ...not sure on the results).

I'm happy. BUT why the he|| isn't this in the owner's mannual?

-Tony