Function of Center Pin on a 7-Way Trailer Connector

Updated 03/22/2020 | Published 11/14/2009

Question:

Etrailer 7 way trailer wiring diagram illustrates the center pole as auxiliary orange while the trailer color codes lists Back Up lights purple and no mention of auxiliary orange. Please explain the center pole. Also is 12volt red/ black the same circuit as battery charger black and Auxiliary what ever color?

asked by: Walt

Expert Reply:

The center pin on the 7 way connector can be used for many different purposes, although it is typically used to carry the signal from the reverse lights on the vehicle to the trailer. If the trailer does not have reverse lights or a reverse lockout for hydraulic surge activated trailer brakes, this pin can be used for any purpose such as providing an additional 12 volt circuit for any accessories on the trailer.

The dedicated 12 volt accessory circuit, # 4 in the 1 O'clock position on the connector, see photo, can be used to maintain a trailer mounted battery, or for any other accessories installed on the trailer such as interior lighting.

expert reply by: Mike L

click to enlarge

Bob

3/20/2020

#4 is in 11 oclock or 1 oclock in that photo

Chris R.

3/22/2020

You're right - looks like we've got a case of a good old fashioned typo. The 12V pin is indeed in the 1 o'clock (from the outside) or 11 o'clock (from the inside) position on the diagram. I will be updating the answer. Thanks for pointing this out!