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Tow Ready 4 Pole to 5 Pole Trailer Wiring Adapter Installation - 2015 Toyota Highlander

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How to Install the Tow Ready 4 Pole to 5 Pole Trailer Wiring Adapter on a 2015 Toyota Highlander


Today in our 2015 Toyota Highlander we're going to be showing you how to install the Tow Ready 4 Pole to 5 Pole Trailer Wiring Adapter, Part Number is 20036. Now our installation's going to begin by attaching our blue wire that's going to come with the kit to the reverse light wire, so that the wire that becomes hot or turns on are reverse lights. Now they're in the door in the hatch of the Highlander here, so we're going to go in to one of the wire looms located inside. We're going to go to the one that's on the left side here, and we'll just pull the boot up of the bracket that's holding it down. What we're going to do is just slide that loom up, get it out of the way now where we can get into our bunch of wires here. The wire that we're looking for is going to be a red wire. The good news is that there's only 5 of them. We only have to test 5 wires to figure out which one's going to be which, it should be this thicker one here but we'll see in a minute.

To test it out to figure out which one we need, we got somebody in the vehicle, of course they've put their foot on the brake, turn the ignition on, and they put the car in reverse. Now we're going to take this regular test light, our ground clamp, we can go right down to the latch that holds the door close. Let's go through it and test wires, with the reverse lights on we should be getting a signal to the wire. Let's start connecting, let's see, all right, nothing on that one, our next here, all right. Now in that red wire I'm getting the signal. What we're going to do is have our partner now take the vehicle out of reverse. Right, it goes off, back into reverse, comes back one, and then out of reverse, so we know that's the wire we're looking for.

Then we take a look here. There's 5 red wires in the loom, this is the thickest of those wire, just to give you an idea of what you're looking for there. Now the wire that comes with the kit, 60 inches long, that's not going to be quite long enough for us to make it down to where we want to go, so we're going to add on just a little length of wire. Just a piece of wire we have laying around the shop here. A little bit larger in size to the wire that we've got there. As we see here it's going to be the same diameter as the wire that we're running. We'll just make a Heat Shrink Butt Connection at the end of those to keep it nice vapor sealed.

We've got a quick connect, quick connect will slide on the wire, take our add on wire and slide on right behind there, hold that bolt together, where we can click that metal tab down. We'll going to squeeze that until that metal tab goes all the way down flush, has a good grip on both of our wires. Then we'll just bring that cover over and click it close. Then what we'll do is just slip that out to our cover here. You can bring that down. It's going to go over the top of that quick connect that we had.

Then I'm going to try to do is bring that wire out through the boot right up here on the top. We'll take a little tiny Philips screwdriver, we'll poke it through there just like that. Tape this white wire here that we've added, I'm going to tape it under the screwdriver and then just try to pull that through that rubber grommet. Take this off, we'll pull the rest of that through. As you're pulling it through you don't want to get too rough with it. You don't really want to stretch that grommet out, we like it to hold right around that wire and give us a nice little seal. Just ease it it on through. All right. As you can see, pretty nice clean looking install. Let's slide that, cover it back on, and try to get it in place. If you see another 4 push tabs, 1, 2, 4, and then 1 on that back side, it's going to be easier to pull that out and get that gasket back around, than it is to fight with it when it's still in there. Just press those tabs and it will come up and out. I'm going to get that stretched all the way around, and then poke it back in just like that, perfect. Now we'll bring our wire all the way around, and what we're going to do to get it outside is I'm going to tuck it right in behind our taillight housing, and run it down and out of the bottom of the vehicle. They'll appear in the top and all the way around there's a nice gasket. I'm just going to tuck that wire right along, behind the back side of that gasket, bring it all the way. As you can see it hides it really well. You can take a pick or a screwdriver or whatever you want, and just work it in all the way around that. You really won't be even able to see it once you get done. Now let's take off the 2 10 millimeter headed bolts that we got, just a 10 mil socket, get in there, remove these out of the back of the taillight housing. Always pull out towards the rear of the vehicle, wiggle it a little bit. If they don't come freely, we'll trim removal tool, plastic screwdriver, plastic spatula, or something. Just work it out a little bit. Basically we've got a little pressure clip right here, then another little clip there. What we'll do is just move this long enough so we can get our wire down past, and we'll continue running to where we can tuck it behind the bumper right here. Place these 2 screws. We've got a piece of airline tubing here, but you can use coat hanger, or a stiffer piece of wire, whatever. We'll just going to run it down alongside here, and see if we can get this to come out below the vehicle where we can grab it and direct the wire down there where we're going to want it. Now we're going to remove the panel here and take a look and see if our pull-wire isn't locate right behind it. To do that we've got 1, 2, 3, 4, and 5 fasteners, you'll need a 10 millimeter socket for them, and then there's just a push pin fastener there. Let's start backing these out. The interior tucked right in here beside the spare. These are just a little push nuts, these are something you can remove just by hand. If they get twisted, a 12 millimeter socket will go over those good. All right. Then the last thing will be a little push pin fastener there, a little screwdriver or pick, pull the center out, and then the outside will come with it. Pull it down, and here we'll see our fish wire which is great. Now let's connect our white wire to it. Here is the white wire, place it right in the end of that tubing, we'll tape it off to your coat hanger, or other wire, whatever you've used, and then just pull away. If starts to get hung here at the top you can pry it out just slightly with a screwdriver, just to allow it to pass in. Then once you get to the wire it should be super simple to drive through. What we're going to do is tape our blue wire off to our white wire. We're going to draw that up slightly, and we want to get our connection where we put our Butt Connector, we're going to hide it in here behind the bumper. That way it's away from any moisture and stuff like that. If we pull up on what we went down, we can get that wire up here and then draw it back in behind our bumper. We want our Butt Connector to be about right in here, maybe right in here, somewhere protected, so that's going to wire down about right there. We'll trim it off, strip the end off, add the Butt Connector, crimp that off, let's strip the end of our blue wire, all right, nice and snug. Now we can take a heat gun, or a lot of times if I'm just doing one like this, I just use a lighter. You want to use the lower part of the flame, so that's yellow and then blue, you try to use that blue part, you'll have a lot less of the black carbon. We'll just heat this up. That's going to start to shrink, there's a nice sealing in there. All right, so nice and sealed off, let it cool for just a second, then for extra little layer of protection with an electrical tape. Get rid of our white wire, we're done with that, now we can use our blue wire to get that pulled down and in. Just like before, with a little pick or a little screwdriver push that back behind our rubber stripping. Now we'll just route our wire, over here towards the 4 Pole connector. Notice the wire loom that runs over for the 4 Pole right here, we'll take a couple of those zip ties there and just secure our wire off here. We don't want it to be pulling down from the tap, give a little bit of slack there. Don't want too much tension on it. We're going to bring that right over here, we got a little bit of extra, which is good in case we ever need any repairs. Zip tie that off there, and that'll leave our connector back here where we wanted. Your customers are going to want to plug into this, so we'll mount it right there, should make it easily accessible for him to get to it. Also keep it up out of the way. Now then just trim off the excess. There's an option to clean up the look of the install, we can take some electrical tape. We just go around that blue wire, it's going to clean it up, make it look a lot more like a factory harnessed one. Right now to test it out what we're going to do is take our 4 Pole Plug in that comes as part of the adapter, you can see here, this is the 5 Pole, here is our 4 Pole. Take our cap off our existing 4 Pole, we're going to slide that in. In here you can see our add on. We're just going to plug in the blue wire from that, right into that reverse light circuit. Now what we're hoping for is that we'll have . The normal lights are going to run right through here, that's not an issue, but we want to test this last one, this fourth, the new add on plug. With our vehicle in reverse, foot on the brakes, somebody in there, we're going to hit it with the test light, as you can see we're getting a great signal. Now we'll be able to plug our harness right into that and have that deactivation when we want it back up. When not in use, pull the plug, and just recap just like that. If you choose to, you can also wire this. This will be tucked up underneath the vehicle, and this will be exposed on the rear. This should work fine with most of the 4 Poles that you'll plug in, unless if it has that rubber shroud that goes all the way around, it may interfere as you try to plug it in. Just keep that in mind if its got that on it. Now our panel need to go right back up where we found it here. Tuck it in behind and then just push it, there it go. The tin push studs here, I like to do those first, I'm just going to push up on them. That'll hold it in place while we get everything else going. All right, with that working at it should that's going to complete the installation of the Tow Ready 4 Pole to 5 Pole Trailer Wiring Adapter, Part Number is 20036 in our 2015 Toyota Highlander. .


Jason C.

10/9/2021

I slightly modified the installation to route the reverse wire to the interior of my 2018 Toyota Highlander, where I had previously wired the 4-pole plug. I simply ran the reverse light wire through the rubber gasket behind the tail light and into the vehicle interior that way. Seemed to work well.

Curtis V.

8/14/2020

I followed the instructions pretty close, but the non-contact signal tester can't seem to locate the wire in question on my 2016 highlander. The tester goes on, but doesn't stay on when touching the wire. Under the gasket there is also a larger red wire attached to a black wire and then a couple other red wires.

Etrailer Expert

Jon G.

8/27/2020

I don't know for sure what color wire you need but if your tester seems to be cutting out then I'd try borrowing one from a friend just to double check and make sure that you have everything wired up correctly.

Curtis V.

8/27/2020

@JonG . Thanks I was talking with a friend and I ended up buying the wrong tester. I ended up with a tester more for higher voltage wires (50-1000v) which is obviously higher than the 12v going through these wires. I also popped off the tail light panels on the inside of the highland and you can see which size and color of wire is connected. I have not spliced into it yet, but it looks pretty straight forward. It would have saved a little more time if I bought an adjustable tester to get down to 12v.

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