[KG4ONJ]

Has anyone installed a 7-pin wiring harness and brake controller on their Highlander? We have a 2014 Platinum that we are interested in using to pull a pop-up tent camper. Most of them require a 7-pin harness and some require a brake controller.

We have a hitch and 4-pin harness installed already. What brands / suppliers have you used that were fairly easy to install?

 

[maybeanotherone]

My HL only has the 4-pin but I installed a Tekonsha P3 to control the 7-pin on my pickup. Easy plus good equipment.

 

[2017Highlander]

If you want a 7-pin, why did you have a 4-pin installed YESTERDAY?

 

[BUFFO]

Has anyone installed a 7-pin wiring harness and brake controller on their Highlander? We have a 2014 Platinum that we are interested in using to pull a pop-up tent camper. Most of them require a 7-pin harness and some require a brake controller.

Look for updates here. Meantime...etrailer.com has install/videos for DIY. If pop up has elect. brakes then you'll need 7 pin. Have used (not my HL) tekonsha b.c. & worked really good.

 

[KG4ONJ]

If you want a 7-pin, why did you have a 4-pin installed YESTERDAY?

Ummmm... What? :dunno:

I installed the hitch and 4-pin 2.5 years ago when we bought the car. Not sure where you got yesterday from.

Thanks to all for the info. I'll take a look at the controllers mentioned..

 

[2017Highlander]

My bad. I could swear I read "yesterday". Oh well, I'll just swear. Lol.

Oh yeah, I have a Tekonsha P3 in the truck...they had a plug-n-play harness for my truck and it works great.

 

[pooder27]

Has anyone installed a 7-pin wiring harness and brake controller on their Highlander? We have a 2014 Platinum that we are interested in using to pull a pop-up tent camper. Most of them require a 7-pin harness and some require a brake controller.

We have a hitch and 4-pin harness installed already. What brands / suppliers have you used that were fairly easy to install?

For the brake controller, I used the Tekonsha 90250 Prodigy RF Electronic Brake Control in my Camry, and I'm glad I did, 'cause I was able to switch it to the Highlander with NO wiring changes. The only thing that it physically connects to is the 7-pin plug; it uses RF to communicate with the tow vehicle.

https://www.amazon.com/gp/product/B001P0ZA86/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

 

[crewzer]

We have a 2014 Platinum that we are interested in using to pull a pop-up tent camper. Most of them require a 7-pin harness and some require a brake controller.

The standard (flat) four-pin connector includes the following circuits:

a) Trailer running lights
b) Trailer left brake/turn light
c) Trailer right brake/turn light
d) Trailer Common

The standard (round) seven-pin adds these functions:

e) Brake controller for trailer's electric brakes
f) Trailer back-up light(s)
g) Trailer battery charging and "house" loads

I recommend careful planning for the trailer battery charging circuit. Specifically, if one just connects this circuit directly to the tow vehicle battery and leaves the trailer harness connected at a campsite, then the trailer's house loads will draw current from the trailer battery and the TV's starting battery. This may deplete the TV's starting battery.

Solutions include a two-circuit diode isolator (alternator-to-battery = one circuit, alternator-to-trailer is the other; example) or a relay to disconnect and isolate the trailer battery circuit when the ignition is off. The latter is how my pickup truck's trailer wiring is configured.

I hope this helps!
Jim / crewzer

 

[chleourdog]

I just installed my 4 pin trailer wiring - (I purchased the factory kit since I already had the factory hitch) - it was very easy to install. As for a 7 pin connection, I have a Hybrid and my battery is in the left rear of the vehicle. If I do install a 7 pin connector, my battery connection wiring will be very simple (no need to run wiring to the front of the vehicle ....)

 

[Redbelly]

.............
I recommend careful planning for the trailer battery charging circuit. Specifically, if one just connects this circuit directly to the tow vehicle battery and leaves the trailer harness connected at a campsite, then the trailer's house loads will draw current from the trailer battery and the TV's starting battery. This may deplete the TV's starting battery.

Solutions include a two-circuit diode isolator (alternator-to-battery = one circuit, alternator-to-trailer is the other; example) or a relay to disconnect and isolate the trailer battery circuit when the ignition is off. The latter is how my pickup truck's trailer wiring is configured.
..............

I prefer the relay, as the solid state devices tend to have an built in voltage drop, which can be significant when you are trying to get as much voltage as possible back to the trailer battery. For the same reason, it is critical to use at least a 10 gauge wire, preferably thicker, all the way from the tow vehicle battery to the trailer battery. The ground wire needs to be just as robust to avoid voltage drops at the trailer battery.

 

[crewzer]

I prefer the relay, as the solid state devices tend to have an built in voltage drop, which can be significant when you are trying to get as much voltage as possible back to the trailer battery. For the same reason, it is critical to use at least a 10 gauge wire, preferably thicker, all the way from the tow vehicle battery to the trailer battery. The ground wire needs to be just as robust to avoid voltage drops at the trailer battery.

All excellent points!

Regards,
Jim / crewzer

 

[sweeneyp]

I prefer the relay, as the solid state devices tend to have an built in voltage drop, which can be significant when you are trying to get as much voltage as possible back to the trailer battery. For the same reason, it is critical to use at least a 10 gauge wire, preferably thicker, all the way from the tow vehicle battery to the trailer battery. The ground wire needs to be just as robust to avoid voltage drops at the trailer battery.

If its diode based (vast majority), it'll have 0.7V drop across the junction. There are a few mosfet based ones out there, those won't have as high of a drop. There is one still, but its almost negligible.

Also use thicker gauge if your going over 30A.

 

[Redbelly]

If its diode based (vast majority), it'll have 0.7V drop across the junction. There are a few mosfet based ones out there, those won't have as high of a drop. There is one still, but its almost negligible.

Also use thicker gauge if your going over 30A.

Right. A 0.7 volt initial drop is a lot when you are trying to charge a remote battery, given that you will have additional voltage drop in the wires to the trailer. This is especially true if you want to run a 12 volt refrigerator while you drive.

 

[sweeneyp]

Size the conductors to further prevent voltage drop then Can't complain about an isolator drop if the wiring was skimped on as its easy to get a similar drop in line losses :thumbsup:

 

[Redbelly]

Size the conductors to further prevent voltage drop then Can't complain about an isolator drop if the wiring was skimped on as its easy to get a similar drop in line losses :thumbsup:

Yes, you have to do both, especially if you want to run a 12 volt refrigerator while you drive. If the voltage from the tow vehicle is too low, the fridge pulls off the trailer battery and you end up with a dead trailer battery at the end of the day.

 

[BUFFO]

Voltage drop

Yes, you have to do both, especially if you want to run a 12 volt refrigerator while you drive. If the voltage from the tow vehicle is too low, the fridge pulls off the trailer battery and you end up with a dead trailer battery at the end of the day.

Your exactly right. Being newbe at the time...drained batt. when running 12V frig. OTR in my OH camper.
I later learned about wiring size etc, but ended up just leaving frig run on propane(turn off when getting gas) My newer TT didn't have 12V frig, just gas/115V. Good discussion by all. :thumbsup:

 

[icebloke]

Great posts. I'm going to jump in here with my plans for my 2016 Highlander. I would appreciate feedback.

My principle is to leave the Towing Vehicle's wiring intact. That means no splicing of cables on the vehicle itself. All splicing will be on aftermarket harnesses and kits.

First, I plan to install the genuine Toyota Harness (PT725-48140). This will provide the 4 pin output required for trailer lights.
Second, I plan to use the eTrailer kit to add 7 pin support as described here https://www.etrailer.com/p-ETBC7.html (There is a video on installing on a 2014 highlander), except for a few deviations from their installation in order to keep the TV wiring intact.

First, instead of quick splicing the brake switch wire under the dash, I plan on quick splicing to pin 9 of the PT725-48140 harness (see the wiring diagram on last page of http://www.landerfan.com/assets/installation/PT725-48140.pdf). This will require that I run a wire from the trunk to the brake controller that will be installed probably under the dash on the driver's side of the vehicle's cabin. Since the eTrailer instructions require running two wires to the front of the vehicle anyway, I though this would not be a big deal. I'll have to use a 3 wire jacket something like this (http://www.rallylights.com/deka-10-gauge-triplex-jacketed-3-conductor-wire.html), instead of the two wire provided with the kit. It will also require that I route this wire into the cabin, which will then be a total of 4 instead of 3 wires going into the cabin.

Second, I am also considering splicing pin 8 of the harness, which is the 12 V hot instead of running the wire all the way to the TV battery. I will then run the wire to the 12 V hot on the 7 pin connector. Since the Toyota harness is protected by a 30 A fuse, I assume that the harness uses 10 gauge wire and that I can use a 30 AMP breaker between pin 8 and the hot pin on the 7 pin connector. Doing this will enable me to only run the jacketed two wire harness provided by eTrailer, one for the brake stop signal to the brake controller and the second from the brake controller to the electric brake signal back to the trailer.

Again, feedback will be appreciated, especially if anyone has done this.

 

[sweeneyp]

Second, I am also considering splicing pin 8 of the harness, which is the 12 V hot instead of running the wire all the way to the TV battery. I will then run the wire to the 12 V hot on the 7 pin connector. Since the Toyota harness is protected by a 30 A fuse, I assume that the harness uses 10 gauge wire and that I can use a 30 AMP breaker between pin 8 and the hot pin on the 7 pin connector. Doing this will enable me to only run the jacketed two wire harness provided by eTrailer, one for the brake stop signal to the brake controller and the second from the brake controller to the electric brake signal back to the trailer.

Again, feedback will be appreciated, especially if anyone has done this.

No. Run a dedicated feed to the battery, don't piggyback off the OEM 12V line for the converter. Its not a heavy gauge wire even with its 30A fuse. Its not much more work, maybe 10min more.

Just use etrailer's kit, 2 underbody cables going to 7way (12V dedicated, trailer brake) coming from the engine compartment, 2 cables going through the wirewall (brake controler 12V and output), and an tiny wire to just sense the brake line at the converter (or tap off the brake switch on the pedal). No need to overcomplicate it.

 

[icebloke]

Thanks. I'll put in the dedicated cables. Hard to believe that Toyota would have a wiring harness connected to a 30 amp fuse without the proper wire gauge.

 

[sweeneyp]

It'll do 30A, just your going to sizable voltage drop as its very close. That and you really shouldn't be tying in trailer const 12V with the main lighting power supply, for safety reasons.