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Factory Trailer Wiring for 2005 Lexus RX330


I have a 05 RX 330 that comes with a tow package. Will it not already have the module and all I need is the plug in cable for the harness? Thanks


Expert Reply:

I'm unaware that the RX330 was available with factory trailer wiring. Must be a pretty rare option.

The photo you provided certainly shows a 4-pole trailer connector. If the wiring harness shown in the photo came with your RX330 when it was new, then there should be a connector somewhere at the rear of the vehicle for the harness to plug in. It looks like there's a grommet on the harness, so the connector might be behind the side panels in the cargo area or in the well where the spare tire is stowed. I couldn't locate any information on where the connector might be located. If you locate the connector, you can plug the harness in and use a circuit tester like part # PTW2993 to see if the connector works.

Connect the alligator clip of the tester on the male pin of the connector. Touch the probe to the socket fed by the brown wire (closest to the male pin) while the vehicle headlights are on. The tester should illuminate. Next, activate the left turn signal and probe the next socket fed by the yellow wire. The tester should light up. Turn on the right turn signal, and test the remaining socket, which should light the tester. The last two sockets should also power up with the brake pedal..

If the harness shown in the photo wasn't included with the vehicle, you'll need to contact your Lexus dealer to find out if the connector will work with your vehicle. If you provide them with your VIN, they should be able to tell you how your vehicle was equipped from the factory.

If you can't find where the connector plugs in, you can use part # 118478 which plugs in behind the taillight assemblies as shown in the installation instructions and video I've linked for you.

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expert reply by:
Mike L

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