Troubleshooting What Wiring Harness Will Work for a 2023 Lexus RX 350
Updated 04/10/2026 | Published 04/04/2026
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Question:
I am wanting to install a trailer hitch on a 2023 Lexus RX 350 Premium Sport Utility, and I’m getting mixed info on how that can be done. I had a hitch and wiring harness installed and after that was done, the lights wouldn’t work because they said Lexus had to ‘activate’ the lights. Lexus told me they don’t do that. So my question is, is there a work around this? I’ve read a ton of forums how other people have successfully done it. I just don’t understand how. Thanks
asked by: Tiffany D
Expert Reply:
Hi Tiffany,
So, issues with the trailer wiring for a 2023 Lexus RX 350 is a common experience that a lot of people have due to an electrical system change Lexus made on the new RX models. The brake and turn signals are sent down separate wires so a powered converter module is required to protect the vehicle's wiring and provide enough power for the trailer lights.
If your vehicle has a factory tow package then a pre-wired plug-in connector like the Curt T-Connector Vehicle Wiring Harness for Factory Tow Package w/4-pole Flat part # 56083 is what you'd need to plug directly into the OEM tow package port that is behind the rear bumper on the driver's side.
If your vehicle does not have a factory tow package, then the vehicle uses a low-voltage, computer-controlled lighting that can't support a plug in harness. Instead, you'll need a wiring harness with a powered converter to read the taillights, pull power, and generate a trailer signal. Currently, we don't offer a custom plug-in harness with a powered converter. However, the most common fix is a universal harness like the Curt Powered Taillight Converter w/4-Pole Flat part # C59236, it requires splicing into the lights and running a 12V power wire to the battery. This will give power to the trailer light circuit and get the trailer lights a useable signal. From the issues you've described, it sounds like a black power line wasn't run to the battery or if they did use a plug in harness, it didn't have a powered converter.
I've attached a video showing an installation of the Curt Powered Taillight Converter w/4-Pole Flat part # C59236 on a 2024 Lexus RX305H for reference to help trouble shoot.
Do you happen to know the brand or part number of the wiring harness that was installed on your Lexus currently?
Product Page this Question was Asked From
Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Vehicle End Connector
- Powered Converter
- Universal Fit
- 4 Flat
- Plug and Lead
- Splice-In
- CURT
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Dane
4/10/2026
On the wiring kit I bought you need to take one wire not sure what color now. But wire into fuse box with a fuse able link so you have power to the rear to run taillights. If dealer didn't do that good reason why it won't work. Be sure you get the directions for wiring from the dealership. Good Luck