Should Aux Circuit on Trailer be Activated and How to Charge Breakaway Battery  

Question:

Helpful Expert Reply:

I can't be certain what the seller meant when he said the auxiliary circuit is dead on the trailer but it's likely that he was referring to the center pin auxiliary/reverse circuit on the 7-Way. You can take a look at the 7-Way on the trailer to see if there is even a wire coming out of this location at the back of the connector.

A lot of towing setups don't require this circuit as the trailer may not have reverse lights so it it is perfectly fine for this lead to be "dead" on the trailer. In many cases the circuit is simply left unconnected like what it sounds like is the case on the trailer. If you see something different please let me know and I will be happy to look into this further.

To charge the breakaway battery on the trailer you will indeed want to use the 12V circuit on the 7-Way to maintain its charge while you're towing. Make sure the wiring from the battery is connected to the trailer 7-Way in this manner. It is also a good idea to test the 12V pin on the 7-Way of your F250 to make sure it is active with the truck running.

I have attached a few diagrams to assist.

expert reply by: Chris R

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