DIY 7 blade wiring on Subaru Outback?

[jeffminnesota]

I was going to go to a local hitch install company to get a 7 blade connection wired on my 2020 Subaru Outback, but then I thought: Maybe I can do this myself ! What do you think? Have you done this? What brand/model of wiring harness? From where? I am not totally without skills, I did a 4 pin once on another car... I think they wanted to charge me about $500 at the shop... I would probably use the AuTowBrake key fob system to control the brakes on the trailer, installed with new axle and brakes by Scamp (13 foot 2002). Opinions?

[Darwin Maring]

https://www.etrailer.com/t1-2020_Sub...back+Wagon.htm

[dfandrews]

Darwin's reference (Post #2 - etrailer site) is a good place to start. What you should look for is a seven pin wiring kit, which includes the wiring for electric trailer brakes.

Look for eTrailer installation videos. They can give you an idea what skills and tools you will need. E.G.: https://www.etrailer.com/Accessories...er/ETBC7L.html

[The Minimalist]

I did my 2014 Outback with the 7 pin kit for e-trailer. Under the hood is not a problem. Under car was not bad until I got to the back where I had to detach a couple of plastic shields to route the wire away from the exhaust and mount the 7 pin to the bumper. Moderate skills should do it. Mounting and wiring the brake controller was straight forward though working under the dash was a little tricky for a moderately overweight old man.

[Alex Adams]

I had the factory 4 pin wiring for my Crosstrek so I didn't need the 4 way flat wiring from Etrailer. I wanted to charge my battery while driving and I also have the Autowbrake system. The adapter I bought on Amazon is unavailable now, but any 4 way flat to 7 way adapter like this one will allow you to run a charge wire and you will still have the brake and accessory wires available to be wired for the future:
https://www.amazon.com/dp/B083L57WG5...v_ov_lig_dp_it

I used a hole saw to create a hole in the plastic bumper and used stainless steel sheet metal screws to secure the adapter:

Be sure to use some dielectric grease on the 4 way connector before plugging it into the adapter so moisture won't get in.

[jeffminnesota]

thanks Darwin, but I was looking for a 7 blade, these are for 4 pin, I understand the 7 blade for the trailer brakes needs a wire direct to battery?

[jeffminnesota]

thanks Don, that looks like it would work, I do have a 4 pin already, was hoping to have both, but that looks like it would work

[Alex Adams]

Originally Posted by jeffminnesota

thanks Darwin, but I was looking for a 7 blade, these are for 4 pin, I understand the 7 blade for the trailer brakes needs a wire direct to battery?

You do not need a wire direct to the battery when using the Autowbrake system. You want to install the Etrailer 4 pin adapter first since it plugs directly into the existing wiring, then use the 4 pin to 7 pin adapter like the one I linked to to get to a 7 pin connection if you want to run a charge line or backup lights. Otherwise you could just use a 4 pin to 7 pin adapter like this:
https://www.amazon.com/dp/B01M18QTHY...v_ov_lig_dp_it

[jeffminnesota]

Originally Posted by The Minimalist

I did my 2014 Outback with the 7 pin kit for e-trailer. Under the hood is not a problem. Under car was not bad until I got to the back where I had to detach a couple of plastic shields to route the wire away from the exhaust and mount the 7 pin to the bumper. Moderate skills should do it. Mounting and wiring the brake controller was straight forward though working under the dash was a little tricky for a moderately overweight old man.

thanks Clif, which kit did you use, if you remember. Thanks for the reassurance from one moderately overweight old man to another. I am going to use the AuTowBrake, so no crawling under the dash, I think I can remove the plastic panels.

[jeffminnesota]

Originally Posted by Alex Adams

I had the factory 4 pin wiring for my Crosstrek so I didn't need the 4 way flat wiring from Etrailer. I wanted to charge my battery while driving and I also have the Autowbrake system. The adapter I bought on Amazon is unavailable now, but any 4 way flat to 7 way adapter like this one will allow you to run a charge wire and you will still have the brake and accessory wires available to be wired for the future:
https://www.amazon.com/dp/B083L57WG5...v_ov_lig_dp_it

I used a hole saw to create a hole in the plastic bumper and used stainless steel sheet metal screws to secure the adapter:
Attachment 140047
Be sure to use some dielectric grease on the 4 way connector before plugging it into the adapter so moisture won't get in.

thanks Alex, I too, want to charge my battery, so would want to run a "charge wire", and I think the AuTowBrake videos I watched said it would work off brake light signal but they recommend running wire to battery.

[Alex Adams]

Are you sure, this is from the installation instructions from Autowbrake's website and how I have power connected to the unit:

Note: Power source

DO NOT USE TRAILER BATTERY OR BREAK AWAY BATTERY FOR POWER SOURCE

If you do not have a 12-volt power line from tow vehicle (example 4 way flat plug instead of a 7 way), you can Use running lights as direct 12-volt power source.

When using this option, you must have your vehicle lights turned manually to the on position, and not use the automatic light feature. You must also know if you fail to turn the tow vehicle lights on while towing you will also not have functioning trailer brakes.

[jeffminnesota]

Originally Posted by Alex Adams

You do not need a wire direct to the battery when using the Autowbrake system. You want to install the Etrailer 4 pin adapter first since it plugs directly into the existing wiring, then use the 4 pin to 7 pin adapter like the one I linked to to get to a 7 pin connection if you want to run a charge line or backup lights. Otherwise you could just use a 4 pin to 7 pin adapter like this:
https://www.amazon.com/dp/B01M18QTHY...v_ov_lig_dp_it

thanks Alex, I should have mentioned I do have a dealer installed 4 pin, was hoping to get a 7 blade in addition as I have some trailers with 4 pin. I thought I remember the AuTowBrake video saying "it will work off the brake light, but we reccommend a direct to battery wire" or something like that, I will have to go back and rewatch the AuTowBrake video.

[Alex Adams]

Definitely use the power wire from the 7 pin if you have it. Be sure to run a large diameter wire, I used fused 8 gauge. Especially if you will be charging the trailer battery.

[jeffminnesota]

Originally Posted by Alex Adams

Are you sure, this is from the installation instructions from Autowbrake's website and how I have power connected to the unit:

Note: Power source

DO NOT USE TRAILER BATTERY OR BREAK AWAY BATTERY FOR POWER SOURCE

If you do not have a 12-volt power line from tow vehicle (example 4 way flat plug instead of a 7 way), you can Use running lights as direct 12-volt power source.

When using this option, you must have your vehicle lights turned manually to the on position, and not use the automatic light feature. You must also know if you fail to turn the tow vehicle lights on while towing you will also not have functioning trailer brakes.

OH. Thanks for looking that up. I will have to go back to the AuTwoBrake video, and also to look at the install instructions, which would be a better source than a video, where (I think the guy was the co-founder or something) might miss-speak-- or I might have mis-understood. Thanks

[gordon2]

Please dont tap into lights or anything like that for powering the trailer brakes. Run a line straight from the tow veh battery to the 7-pin, with a self resetting circuit breaker at the battery end. This applies whether using the AuTowBrake controller, a traditional brake controller or any brake controller for electric trailer brakes. You dont want to take a chance of overloading a circuit that was never designed to power the brake magnets, let alone do who-knows-what to the vehicle's electrical or computer system.
You can use an adapter to go from the 4 to 7 pin for lights then add the brake power and / or charge line.

[Lynn Eberhardt]

You might consider a voltage sensing relay in the charge line. It's on only when the tow vehicle is running. You won't kill your TV battery if you don't disconnect while camping.

[The Minimalist]

Originally Posted by jeffminnesota

thanks Clif, which kit did you use, if you remember. Thanks for the reassurance from one moderately overweight old man to another. I am going to use the AuTowBrake, so no crawling under the dash, I think I can remove the plastic panels.

I installed all this in 2013, so I'm not sure which kit I ordered. However, I looked on the e-trailer site and I'm pretty sure I would have ordered the ETBC7. This kit has everything you need to hook up the wiring for the lights and the trailer brakes. If you ordered your Outback set up for towing, this kit allows you to connect the 4-way connector to the 7-way and, voila, you have lights; tail, brake and turn signal. Also, it comes with the wire and circuit breakers to properly power the brake system. The two wires are encased in a heavy cover to prevent damage from road debris. Also, I ran mine along the side of the longitudinal strengthening members to better protect them. Also, due to aesthetics and the low ground clearance of the Outback I mounted the 7-way plug right into the bumper, rather than use the supplied mounting bracket.

[Patrick PDX]

Regarding the power wire of a 7 blade trailer hitch: One thing to consider when deciding to charge your trailer battery with your TV is if the automobile’s alternator can handle the continuous amp draw needed to charge a deep cycle battery and the car battery at the same time. Alternators are usually rated to top off a standard car lead acid battery- which has low amp hours but high cold cranking amps. I’m guessing this results in a short duty cycle to get the car battery charged. Charging a deep cycle that’s been discharged (even a nominal amount) might cause the alternator to overheat and shorten its life if it’s at a constant duty cycle trying to “fill” that battery. As well, you would need to have heavy gauge wiring from alternator to trailer and some kind of solenoid or dc to dc charger to isolate both batteries from each other to protect the car battery from over charging or the trailer from discharging the car’s battery.