What Is Needed To Add A 7-Way To A 2018 Volvo XC90?
Updated 09/29/2025 | Published 05/14/2025
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Question:
I have a 2018 Volvo XC 90 and need a seven pin trailer towing wiring harness. Currently, I do not have a four pin which product would you recommend?
asked by: Wade L
Expert Reply:
Hi Wade!
We can definitely get your 2018 Volvo XC90 set up with a 7-Way plug. You will need to start with a 4-Flat and for that I recommend the Tekonsha T-One Vehicle Wiring Harness # 118683. This will supply the needed power to the trailer lights. From there, you can add on a 7-Way like our universal kit # ETBC7 (there are no plug and play options for a 7-Way for your vehicle, unfortunately). Installing this will take a bit of work, but it's not over difficult. I included a picture below that shows how it is done as well as an install video on a 2016 XC90.
If you are only needing the 7-Way for power, then you will not need anything beyond this and the blue wire in the diagram (Electric Brake Output) will not need to be run. But, if what you are towing has brakes, you will need a brake controller to engage them. I have 2 options listed below in case you do need one.
My personal favorite:
Redarc Tow-Pro Liberty Brake Controller w/ Universal Wiring Harness # RED52VR
Easiest to install:
Curt Echo Wireless Brake Controller - 7-Way Plug-in w/ Bluetooth App # C51180
The Curt controller will just plug in-line with the trailer wiring and 7-Way plug and after installing the app on a smart phone, it's basically ready to go. As it does not physically connect to anything in the vehicle, that blue brake controller output wire will not need to be run for this controller.
The Redarc controller will need that blue wire run and you will need to install in the vehicle and the control knob will need to be somewhere easy to reach. As this knob is how everything is controlled, it will need a hole drilled into the dash for it to fit. We haven't installed this in a Volvo yet, but I included a video we did on an VW Atlas for you to check out. Redarc controllers are arguably the best on the market, at least in my opinion, and it is well worth the more difficult install.
I know this can be a lot to take in, so feel free to comment below if you have any questions!
(click to enlarge)
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Lazer S.
9/29/2025
Hi Wade, Did you get a chance to install the Tekonsha wiring harness and the 7-Way kit on your Volvo XC90? I'm curious if you found the process straightforward and if you decided to go with one of the brake controllers. Your experience could really help others who are setting up their towing system.