Installing a Universal Trailer Wiring Harness on a 2007 Lexus RX 400h

Question

Question:

Your instructions, both hard copy and online, are inadequate for this vehicle. Lexus forums report that there may be a prewired connector for this, though I havent found it on mine. Access to the wiring harness is not described at all by your materials, and that seems essential to choose a good mounting point for the circuit and splice points for the wiring. Please provide something that is actually written/photographed for this car and not generic wiring diagrams.

asked by: Thomas M

1

Helpful Expert Reply:

The Wiring Harness, # C59496, that you purchased is a universal wiring harness that can be installed on many different vehicles. That is why the instructions are generic and not vehicle specific. At this time there are no vehicle specific aftermarket wiring harnesses available for the 2007 Lexus RX 400h.

We have not had the chance to install a trailer wiring harness on a Lexus RX 400h yet so I do not have written material or photos, but I can give you some tips on where to find the tail light circuits to splice into. The easiest place to find the tail light circuits is directly behind the tail light assemblies. You'll want to access the harnesses feeding the taillight assemblies by removing your taillight assemblies, which should be outlined in the owner's manual.

Once you have the tail light assembly out, you will see wires going into the back of the tail light assembly. The wiring kit that you purchased came with a circuit tester. You will want to probe the wires to determine which wire carries which function. Unfortunately my wiring harness manufacturers do not have specific color and function information for your vehicle, so testing the wires will be the best way to ensure you are splicing into the correct wires.

When installing a universal wiring harness, how the wiring harness is installed is at the discretion of the installer. You may find that there is not enough room behind the tail light to mount the converter box, so you may need to look into other mounting options. If there is room under the vehicle, you may be able to mount the converter box somewhere under the vehicle (preferably in a dry location away from dirt, water and other elements) and feed the wires up to the tail light assemblies.

expert reply by: John H

1

Answer 1

The first thing you need to install a 7-way on your 2008 Lexus RX 400h is actually a 4-way with #C59236 which you will then convert to a 7-way with the part #ETBC7L which comes with everything needed to have a functioning 7-way with the 12 volt…

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Answer 2

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 3

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Answer 4

The OEM prep package consists of 4 "pucks" in the bed of the truck that will allow you to drop in puck style hitches for easy installation and removal, that gives you a completely clear bed when not in use. The B&W Companion OEM 5th…

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Answer 5

If you just need a 4-pin to 7-pin trailer wiring adapter, then you can use part #C57672. This will plug into the 4-pin trailer connector on your brother's vehicle and give him the 7-pin socket for the trailer. Keep in mind, this will only give…

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Answer 6

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 7

Hey Antoine, so the two kits you mentioned are actually really similar and honestly I would go with the part #ETBC7 if I were you. The #ETBC7L is basically the same thing minus a couple wires and breakers so you may as well get the kit that has…

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Answer 8

If you have a vehicle specific wiring harness for a brake controller then that would indicate that you have a factory tow package and subsequently would already have a 7-way at the back of your vehicle. The universal 7-way connector #ETBC7 is meant…

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Answer 9

I would be happy to help you set up your 2022 Toyota Highlander to haul your new travel trailer. The wiring harness you currently have controls your trailer's lighting functions only. You do not need to rewire your Toyota you just need another…

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Answer 10

Yes, we do. To add a hitch to your 2024 Toyota Grand Highlander, I recommend the Curt Trailer Hitch item #C26VV. This hitch is custom fit and bolts to your Toyota with included hardware. This is a class III hitch with a 2" receiver. It has a…

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Answer 11

The first thing you will need for your 1999 D250 is a 4-way. The Curt T-Connector Vehicle Wiring Harness #C55317 plugs into the connection points behind your rear bumper and will allow you to power your trailer's signal lights. Once the 4-way is…

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Answer 12

You will have to go with a sliding hitch to allow the trailer to make tight turns. For a trailer 8 feet wide the only bed length that's going to allow 90 degree turns without a slider is a stationary hitch. That being said you have two options.…

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Installing a Universal Trailer Wiring Harness on a 2007 Lexus RX 400h

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