Trailer Wiring Harness Adapter to Convert 4-Pole to 7-Way to Allow Charging Trailer Battery

Updated 02/23/2015 | Published 02/21/2015

Products Featured in This Question

Adapter 4-Pole to 7-Pole and 4-Pole

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10 Gauge Wire - Blue Primary - Per Foot

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40 Amp In-Line Circuit Breaker - Perpendicular Mount Bracket

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Deka Ring Terminal - 12-10 Gauge - Size 10 - Nylon Insulation - Yellow - Qty 1

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Question:

I have a 2013 Sienna LE that has a four wire trailer light harness. I just purchased a Scamp 13foot travel trailer with no trailer brakes but it does have an additional battery on the tongue of the trailer. The trailer has a round 7 wire connection where the brake pin has no wire. How do I convert the toyota wire lead to the round 7 wire connector so I can hook up the trailer lights and battery to the alternate of the van?

asked by: Gerry

Expert Reply:

To convert your Sienna's flat 4-pole trailer connector to a round 7-way RV-style that includes a circuit for charging a trailer battery you will use Hopkins part # 37185. This simply plugs in to your existing 4-pole and will then carry the same lighting signals. In order to have a 12V charging circuit active on the 7-way you will need to add a connection for that new circuit.

You will also need 10-gauge wire, part # 10-1-1; a 40-amp circuit breaker, part # 9510; as well as ring terminals # DW05762-1.

The white ground wire's ring terminal from the 7-way connects to your Sienna frame, to a clean bare metal spot; the circuit breaker installs between your battery positive terminal and the black wire on the 7-way. Please refer to the linked photo which shows these two wires, noted with red arrows. The other wires can be tucked out of the way until such time as you need to activate them for other trailer functions.

expert reply by: Adam R