Troubleshooting No Power at Factory Port on 2017 Lexus RX 350 without Factory Tow Package

Question

Question:

I purchased the tow package and the wiring harness, connected the harness to the receptacle under the vechicle bumper. No current coming through the harness. This vechicle did not come with factory tow. Any aolutions?

asked by: Robert

1

Helpful Expert Reply:

If your 2017 Lexus RX 350 didn't come with the factory tow package then an additional harness with a powered converter is needed to actually activate the plug that you used to install the Tekonsha T-One Vehicle Wiring Harness # 118252. This Tekonsha harness is designed for vehicles that came equipped with the factory tow package.

Unfortunately, the converter harness is not available as a separate item from the manufacturer so your only option is to get the Tekonsha T-One Harness # 118255 instead, which is designed for the Lexus RX 350 that doesn't have the factory tow package. This particular harness includes the needed power module harness that plugs into a factory port behind the interior trim panel in the rear cargo area.

I have attached the written installation instructions that you can also check out.

expert reply by: Chris R

1

Brett

6/8/2026

So this site seems to contradict. Here you are saying part #118255 is for the Lexus without the tow package. Yet look up that part and on that page is says opposite. Must have factory tow package first. I am so confused and just want something to get power to trailer harness.

Chris R.

6/9/2026

@Brett Hey Brett! So....this is really confusing and I apologize. Bear with me. The original 118255 part number you mentioned references a wiring harness from Tekonsha, which is no longer available. It looks like when typing in that part number now it's bringing up a suitable alternative from Curt (part # 56083), which as you discovered, is actually for the RX 350 that includes the tow package, just adding to the confusion. I am working on getting this cleaned up on our site. All that being said though, for your RX 350 WITHOUT the tow package, the correct wiring harness is the Curt # C36PQ. This includes the needed powered converter box and will still plug right into the factory harness on the Lexus.

Brett

6/9/2026

@ChrisR ok got it! Thank you!

Answer 1

I'm not sure what wiring you purchased but if it's anything like the Curt T-Connector #C56217 for a 2021 Lexus RX 350 without the tow package then the system should be working once you get the module and fuse installed. If you aren't…

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Answer 2

Aside from what you already found, the best advice I can offer comes from another customer who installed the #118255 on an RX 350. On the inside corner cover, pry up the center of the black plastic fastener and remove it. Reach under the cover with…

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Answer 3

The trailer wiring harness #118252 is designed to fit a 2012 Lexus RX 350 that came with the factory tow package. If your RX 350 did not come with the factory tow package then harness will not work. If you are unsure if your model has the factory tow…

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Answer 4

For your 2017 Lexus RX-350, I recommend the Curt Trailer Hitch Receiver - Custom Fit - Class III - 2" #C73DR. For your trailer wiring, I recommend the Curt T-Connector Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer…

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Answer 5

The Curt Trailer Hitch Receiver part #C13143 is an excellent option for your 2015 Lexus RX 350 and will work well for you. It has a Class III rating with a 2" receiver tube opening. It also comes with a limited lifetime warranty. I have attached…

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Answer 6

Yes it does. Our website can be fun sometimes. I can confirm that the Draw-Tite Trailer Hitch item #75540 does fit the 2019 Lexus RX 350 including the F Sport model. I have linked an installation video below so you can see how to get it set up. If…

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Answer 7

The T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part #118255 is designed for a 2017 Lexus RX 350 without a tow package. Since the vehicle does not have a tow package there should be a 10-pin connector located behind the rear…

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Answer 8

The 2015 Lexus RX350 could have come with a factory tow package meaning that it would be prewired for a trailer wiring harness which is what that other company that isn't nearly as awesome as us is saying. Models that do not have the factory tow…

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Answer 9

Yes, that is consistent for your 2014 Lexus RX 450h as well. I checked the online owner's manual for your vehicle and the fuse locations were the same. You can verify this with your copy of the owner's manual as well. I found the fuse…

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Answer 10

The Curt T-Connector Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector #56083 is only a fit for a vehicle with the factory tow package. If you have the factory tow package, then you may have fuses that are missing or bad.…

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Answer 11

Though the best way to verify 100 percent if your 2012 Lexus RX 350 is to place a quick call to your Lexus dealer with your VIN, you can also look under the bumper to the left (driver's side) and see if you have a panel that can be removed where…

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Answer 12

Yes, the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector #118255 will fit your 2015 Lexus RX 350 that does not have the factory tow package.

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Troubleshooting No Power at Factory Port on 2017 Lexus RX 350 without Factory Tow Package

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