Best Trailer Wiring Harness For A 2017 Toyota Sienna XLE  

Question:

Expert Reply:

Hi Terry!

This is probably the easiest question to answer I have received in a couple weeks! Hands down, the best option is the Tekonsha. Specifically the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118648 for your 2017 Toyota Sienna XLE. I have been doing this for over 10 years now and have found the Tekonsha wiring harnesses to be the most reliable and longest lived aftermarket wiring harnesses on the market. They are the ones to get when they are available.

This is plug and play, so it's easy to install and we even have an install video of this going onto a 2017 Sienna, which I included for you to check out. The most difficult part of this install will be running a wire up to the battery for power. It isn't really that difficult, just a bit tedious.

Do you already have a hitch on your Sienna? And what are you going to be towing?

expert reply by: Lazer S

0

John P.

2/13/2026

The wiring harness was all good except, I e trailer know that the wire going to the battery from the rear was not long enough, and I had to splice a wire in which I felt was ridiculous for the price of this product.

Lazer S.

2/18/2026

@JohnP Sorry about that. Little surprised that happened. We typically have to cut off a decent amount of excess wire when we do these. Do you mind if I ask how you ran that wire?

John P.

2/18/2026

Yes, I ran from the right rear light group across rear to the driver side rear interior up to front and through firewall to battery. Behind rear moulding and tucked under side and floor moulding as direct as possible to battery.

Lazer S.

2/18/2026

@JohnP Interesting. I would have thought there would have been enough to do it the way you did, even with the Sienna being a relatively long vehicle. Sorry you had to do that, but thanks for letting me know. I would bet someone down the road will read this and take heed.

Scott H.

2/13/2026

I installed this in my Toyota 2015 Sienna. Installation was simple, connectors plugged directly into the tail light connectors. I leave my flat cable stored inside the tire tool compartment and then take it out the door hatch when I use it. I also installed my own wire and plastic wire tubing with inline fuse at the battery connector.