bentley311

Hello all,

I have done a lot of digging around on this topic, but I have not found anything that answers my question to this point. I have to assume I am not the first to want to have a 7 pin connector set up to tow a small RV with Trailer brakes, but I cannot seem to find information on what is required. It is my understanding that the existing wiring harness allows for a 4 pin connection, and then I would run a conversion with wiring that goes to the front battery and also to a brake controller.

As far as the brake controller is concerned, I am being told by an eTrailer rep that I need to use an RF style brake controller (way more expensive than the others and has features I do not need) due to a brake light setup issue on the 2007 RX400h. Does this sound accurate to anyone else? Has anyone successfully installed the wiring for a camper or some other 7 pin plug with trailer brakes on this model Lexus that could share with me what they went with?

Appreciate any insight on this.

Regards,
Chris

smassey321

I converted my 4 to a 5 pin plug with these instructions. https://www.clublexus.com/forums/rx-...-location.html

I believe the hybrid brake lights are turned on by the ECU rather than a traditional switch. It has something to do with the electric brakes knowing you are pushing down on the pedal. Perhaps you can add a RX330 brake light switch to your RX400h? Or even a 2nd switch to isolate the braking systems.

How heavy is your trailer? Most mid size (~3000 lbs) trailers i see have surge brakes.

bentley311

Thanks for the response smassey. The trailer is not that heavy. It is only about 1200 lbs. Still seems odd to me that Lexus would make the towing capacity of either 2000 or 3500 lbs depending on whether the towing package is installed, yet not have a way for people to tow a trailer with trailer brakes with a 7 pin connector.

I am holding out hope there is someone out there who has done this and can explain what they have done.

bentley311

So I am still hoping someone else out there has wired a trailer at all on a 2007 RX400h that does not have the towing package installed. I found the wiring in the back yesterday, but there is no power coming out of any of the leads. In contacting Lexus, they told me there is likely a power converter module needed (yet they did not know of a specific part for this ironically).

I have to assume that someone out there has installed at least 4 pin wiring to this model before given that it has wiring run to the back and is rated to tow 2000 lbs, but I am at a loss currently on what needs to be hooked up to the provided connector to get power? Even Lexus does not seem to know which is baffling to me.

Can anyone out there shed some light on what they have done?

Thanks!

jakenbake

I don't know about the trailer brakes but I can say the hybrid brake lights still have a conventional brake switch.

HtownBlue

You can easily wire your own. The only trick is to properly wires each wore lead for the correct function (ie constant power, brake switch, running lights, etc etc.

Most trailers are similar in the way they are wired. The critical thing when doing your own wiring is to make sure of two things: each wire from the vehicle is properly wired for correct function on trailer, and to make sure the voltages being pulled BY THE TRAILER WHEN EACH FUNCTION IS ACTIVE are correct for the amps you are wiring into. If the Active brake function needs 40 amps for instance, don't wire that lead to the break lights that pull 20 amps. For constant power you can wire directly to the battery with an inline fuse.

I wired my own hitch etc on my RX330, and plan on doing the same on my 400H.