JDWhite

We have a 2015 RX350 without a Tow Package, is it possible to install an After-Factory Tow Package?
Currently our towing capacity is 2000lbs would like to increase it to 3500lbs.
Any knowledge or experience with this would be appreciated.

Clutchless

It would be very expensive and I would rather just trade it in. You need to add the oil cooler, plus the transmission cooler which is inside the radiator. Plus the wiring for the hitch. The hitch itself if you get a Curt at etrailer like most folks is cheap at under $200. Yeah, maybe a hitch shop could add the extra coolers for less than a dealer. However it is a 5 year old vehicle with we don't know how many miles. It may not be a good investment at this stage of its life to add all that stuff.

Non

I read somewhere that all the 2015 models came with the towing package standard, so double check that yours doesn't have it. The towing package does not include the trailer hitch btw, I'm not sure if you realize it.

Clutchless

You can inspect it yourself to determine if you have the oil cooler. There are metal oil cooler lines near the oil filter. If you look at the images in this link you can see what it looks like and where it is located. You will have to lay on the ground and look up under the front bumper into the engine bay. It is in the center front toward the passenger side a bit. https://www.google.com/search?q=rx35...w=1536&bih=714

The other thing to look for is the transmission cooler. It has vents inside the front inside area of the driver side wheel fender liner.

Or ask a shop or dealer to check it out.

EdwardJd

My RX350 FSport 2015 has tow package, but it doesn't have trailer hitch. So I removed tow package, then installed a class 3 trailer hitch with 2" receiver (#14143). According to the manufacturer Curt, this trailer hitch is rated to 4,000.00lbs & 400 lbs tongue weight. Because the tow package couldn't be installed with the trailer hitch at the same time, I had to remove it before installing the Curt trailer hitch. The installation is not really hard for non-technical like me, but it takes time & we have to trim a underbody panel. I watched a video clip on youtube showing the installation for a similar trailer hitch for 2015 RX350. I did myself with the help of a few retaining wall blocks.

Back to your car, absolutely you can install an after market trailer hitch regardless of tow package.

Here's is the link of video that I watched:

Kansas

Nice clean install. If that's a 4-way connector cable I see wound around the receiver, Hopkins has a bracket (part number 48595) that's perfect for situations like this. One could probably be attached to the same plastic panel that you had to notch - maybe on the left side of the receiver. Here's a photo of one installed on one of our vehicles. IIRC, I think the screws that came with the bracket were self tapping which were useless for attaching it to a plastic panel. I used shorter screws with nuts to hold the bracket in place. I wrapped the 4-way connector with electrical tape so that it wouldn't wiggle in the bracket - might not be necessary on yours. I paid only $4 for the bracket at Advance Auto but it's widely available online.

EdwardJd

Very nice & neat install, I'd that. This install hires wiring cable & the socket perfectly. In fact, I have 2 brackets (one from Curt & another one from ETrailer), but I don't know how to attach it to my car. Their instruction shows that the bracket should be screwed into the trailer hitch, but it's not applicable in my case. At first I'd really don't like to attach by scrvewing it directly into the underbody plastic panel, because I feel it's not stable. Seeing your install of bracket, I think I should do the same way you did. Thank you for sharing, Kansas.

Kansas

Use some decent size flat washers on the upper side of the plastic panel before installing the nuts on the screws you use. That should get the Hopkins bracket rigidly connected to the panel. You might want to use lock washers between the flat washers and the nuts.

Some brackets sold for mounting 4-way (and 7-way) connectors attach to the receiver hitches cross beam. That works fine for an exposed cross beam but not as well for a hidden cross beam like your Curt hitch has. You might be able to attach one of your current brackets to the hidden cross beam (e.g. with zip ties) but you'd have to cut an opening in the plastic panel so you could plug in your trailer's 4-way connector. The surface mount Hopkins bracket makes it especially easy to plug in a trailer's 4-way connector. There are other brackets that could be attached to your plastic panel's surface but the Hopkins was the best one I've found in that it has the lowest profile and is least likely to get caught on a curb or something else and do damage. Fun stuff, eh?

JDWhite

We have already installed a hitch but only use it for our bike rack, we want to install a tow package to ensure the vehicle has the power to tow a travel trailer.

Kansas

Then you might want to go directly to a 7-way connector and mount that under the bumper cover, plastic panel or on the receiver hitch cross bar. Some 7-way connectors also have a 4-way connector built in to them which is nice to have if you ever want to tow a smaller trailer like a U-haul. The 4-way connector you have now won't be wasted since it will plug into the back of many 7-way connectors as a starting point and then you'll run 3 more wires from the 7-way connector. Etrailer is a great place to buy stuff like this - great tech support ... handy for me since they are close and I often get next day delivery.

Clutchless

I think JDWhite is more concerned with the ability of the engine and transmission to handle the towing load without the additional cooling features provided by the factory tow package. Many trailer hitch shops could install an extra transmission cooler and that may be enough to help with towing. Your 2 options are an aftermarket cooler or a replacement factory style radiator which has the transmission cooler built into it.
For the engine oil cooler you would have to find out the price of the parts for the factory oil cooler and installation costs. Maybe the same tow hitch shop could help, or a good repair shop.

Kansas

Sorry, I missed that his RX doesn't have the tow prep package. Someone on the Sienna Chat forum said a few years ago that the estimate he got to add an OEM engine oil cooler to a V6 engine that didn't come with the tow prep package was extremely high but I don't remember how much. I looked up the parts today and saw that different cylinder blocks are used in both the gen 3 Sienna and gen 3 RX when an engine oil cooler is installed. It's not a matter of just plugging in an OEM engine oil cooler on a cylinder block that isn't made to accept one.

Skier76

I believe there are some threads over on Toyotanation.com in the Highlander forums where people have added the trans cooler. It should be a similar procedure on the RX.

Clutchless

They are in the 2008-2013 Highlander forum under the DIY: Maintenance and Modifications header. You have to scroll down a bit to find the links to 2 different transmission cooler DIY threads and just below those links are more info on hitch wiring variations.