Installing 12 Volt Power Circuit to 7-Way Trailer Connector on Rear of Tow Vehicle

Updated 11/08/2016 | Published 11/07/2016

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10 Gauge Wire - Blue Primary - Per Foot

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Pollak Circuit Breaker - Cycling/Automatic Reset - 40 Amp - Straight Mount Bracket

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Question:

How can I get center pin hot to maintain trailer batteries?

asked by: Skip

Helpful Expert Reply:

Generally, the center pin on a standard 7-way is used for reverse lights on the trailer. However, not all trailers have reverse lights and essentially you can wire the extra pin anyway you'd like. Normally, the pin in the 1 O'clock position when looking into the vehicle side connector is for 12 volt power which would be used to maintain your trailer batteries.

If your tow vehicle does not provide any 12 volt power to an existing 7-way connector it could be because there are fuses or relays that need to be added to supply power. Check your owner's manual for their locations. If the fuses and relays are good, or if there is no wiring going into the back of the 7-way, you can use # 10-1-1 (which is sold by the foot). Connect one end of the # 10-1-1 and route the wire under the vehicle to the front near the battery.

Near the battery you will need to install a 40-amp circuit breaker, # PK54540 to clean metal surface. You will then need to connect the end of # 10-1-1 to the breaker, and run the additional wire from the breaker to the positive battery post.

expert reply by: Charles S