4-Pole Trailer Wiring Harness Fit for 2015 Toyota Sienna  

Question:

Helpful Expert Reply:

The correct Curt 4-pole trailer wiring harness for your 2015 Toyota Sienna is their part # C56106 if you have the SE model or part # C56261 if your Sienna is NOT the SE model. Both are powered converters that provide isolation and protection for your new car's wiring by drawing the actual power for the trailer lights directly from the car's battery. The car's internal wiring just acts like a switch to trigger the harness to draw that power from the battery.

This is important protection for your car. If there were to be a bad short or other fault in the trailer wiring the powered harness will take the hit. Replacing the harness is MUCH less costly than having to have your Sienna's wiring repaired.

Both harnesses install in the same exact way as shown in the linked video. Most of the installation is simply plugging connectors together at the car's taillights. I suggest using dielectric grease to keep those connections free of moisture; part # 11755 is suitable. Apart from the plug-in connections there is a white ground wire with ring terminal that you will affix to a bare metal surface; and there is a black power wire that you'll run up to the engine compartment, to the included fuse holder and on to the battery's positive terminal.

To help you route that power wire I have linked an article that details ways to do this as simply as possible.

Both Curt harnesses deliver the same maximum current output for the trailer lights: 3-amps per stop/turn circuit and 5-amps for the running lights. If you can, compare this current capacity to the power requirements of your trailer's lights. This will let you confirm that the trailer's lighting will not draw more power than the harness can deliver. Both Curt wiring harnesses carry a 1-year limited warranty from Curt.

Harness # C55580 that you referenced fits Siennas for model years 2004 through 2010 only. Your 2015 model year is part of a different vehicle generation (the third) and so it cannot use that harness.

expert reply by: Adam R

1

Mitchell

7/6/2020

Can I use this connection with a 5 prong harness to light the lights and turn signals while excluding the back-up lights?

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Chris R.

7/10/2020

I believe you're asking if a 4-Way on your tow vehicle can hook up to a 5-Way on the trailer (if not - just let me know). The answer is a big yes! The two connectors are physically compatible with each other, you just won't have that 5th pin active, which carries the reverse signal light signal.

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