Installing Trailer Brake Controller and RV Charging Wire

[BigFoot48]

Hmmm, I've rarely been first at anything!

Introduction and Installing Adapter

I recently purchased a 2007 Odyssey and had the dealer install the Honda towing package as part of the negotiated purchase price. To complete the package for towing the small RV trailer we have, I installed the trailer brake controller and battery charging wire. This is that story.

I had done the same job on our 2004 Element, and it is not particularly difficult although the fit and finish of the Odyssey required me to modify my intended method.

Task #1: Install a 7-pin trailer socket to replace the 4-pin socket that came from Honda.

I picked a "4 to 7 pin adapter" at Wal-Mart. I got the one that has both the 7-pin socket and a 4-pin socket (for utility trailers), for about $23. This is fairly pricey because of the double socket. If you don't anticipate needing the 4-pin socket, or are willing to just unplug the Honda connector from the adapter should you ever need it, you can get a less expensive adapter.

It looks like this installed:


The existing Honda 4-pin plugs into a female socket on the wire harness, leaving only three wires to be hooked up: brake, charging and ground. There is a fourth wire which is for trailer back-up lights, but I don't use it (currently!) so it remains unattached.

The wires coming out of the socket have "bullet" connectors but I was unable to find crimp-on connectors to match so I ended up cutting off these provided connectors and using insulated male/female connectors from Ace Hardware. Cutting off the connectors also allowed me to adjust the wire lengths, so not totally a negative.

Mounting this hitch socket on the Honda bracket was a bit of a challenge. I ended up using a 3" "L" shaped shelf bracket and the existing hole on the Honda bracket.

Task #2: Install +12 volt power line for trailer

A 12V power line is used primarily to charge the trailer battery while the car is running.

On my Element I was able to find a grommeted hole in the firewall and feed the charging line through that, along the inside of the car, and out the back to the hitch.

No such luck with the Odyssey. This firewall is the most closed, tight and secure I've ever seen, and openings are few and far between. One person on this forum said he found a wire harness opening behind the glovebox and used that. I saw that wire bundle but didn't want to remove the glovebox and assorted items.

So, I went underneath the car. This is not my preferred method, and I'm not real happy about it, but I believe the wire is safe and secure, and will probably not get damaged and explode the car.

Other trailer owners with Odysseys have done the under-car route with no problems, so that egged me along.

Here's the picture of the wire connecting to the battery.


The wire is 10-gauge purchased at Ace. (Red would have been a better color.) There is a 30-amp fuse from AutoZone that starts the line by connecting to the battery with the handy screw that is there. It is then connected to the 20' of wire (20' is "just" enough, I recommend 25') via crimped connectors that have heat-shrinkable insulation. (An expensive connector I saw at AutoZone and just had to try. Back to regular heat-shrink tubing next time.)

You can see the wire heading to the right where it goes around the air filter and back toward the center of the firewall. It then goes down where I found some other cables and wires protected by a skidplate. I loosened the skid plate (its small) to get the wire fed behind it, then it is run back along side the frame member.

Sliding under the car and running this wire, attaching it to other cables or wires using zip-ties, is a bit of a pain. It would be a breeze on a lift or ramps, and I recommend that if you go this route.

Here's a picture under the rear bumper on the driver's side where the charging wire joins up with the brake wire, ground wire, and the Honda-installed wire bundle to head to the hitch which is that thing in the background.

[BigFoot48]

Task #3: Locate and install Brake Controller bracket

This is not difficult, but I don't know which I dislike more, trying to slide under the Odyssey to feed the 12v power line, or turning upside down under the dash to install the brake controller wiring harness.

The first task is to determine where one wants the brake controller installed. Some have installed it in the center console storage area, or a glovebox. I want it closer for immediate access if emergency braking is required. I found there were already two screws at the bottom of the dash to the left of the steering wheel, I so decided to use them.

I have the Prodigy Brake Controller, which has worked very well for us in 20,000 miles of towing with the Element.

Here is the result. It is accessible and I have yet to hit it with my leg. I don't have it plugged in and you can see the wiring plug.


Another picture of the bracket.


Task #4: Install controller wiring harness

Remove the drivers side panel to get to the fuse box and make wiring easier.


The harness for the Prodigy connects to 1) a +12V source, 2) the wire on the brake switch that is +12V when the brake is pushed down, 3) a ground, and 4) finally to the hitch connector.

All the wires from the harness have connectors crimped on so that it can easily be removed from the more permanent wiring described below should it be desired.

I used an voltmeter to locate which wire on the brake switch showed voltage when the brake was pushed. Someone said it is a white wire with a brown stripe, and that sounds right. Using a wire-tap connector you connect to this wire a couple of inches back from the switch as shown here:


Here is the connector for the tap put on the brake switch.
http://i164.photobucket.com/albums/u...pConnector.jpg

Here's where I connected the ground wire for the brake controller.
http://i164.photobucket.com/albums/u...llerGround.jpg

Here's the drivers side fuse box. No un-used fuses or +12V hot spots to be found!
http://i164.photobucket.com/albums/u...BoxDrivers.jpg

On my Element I was able to find a +12V (when running) source near the fuse box. On the Odyssey the design and construction is so tight and neat, that I resorted to a Add-A-Tap connector that plugs into a fuse slot and provides a power source. Note: Prodigy recommends connecting directly to the battery.

These little taps are limited to 10 amp and I confirmed the maximum draw for the Prodigy was 7-8 amp. Prodigy, however, specifies a 20 amp auto-reset breaker for their controller, so I used a 30 amp fuse in the Add-A-Tap so the breaker is controlling things. If anyone has a better solution to a +12V power source, I would be interested.

Here's the tap in the Accessories fuse slot. Note you can see the silver breaker among the wires.
http://i164.photobucket.com/albums/u...ontroller7.jpg

The white ground wire is connected to a bolt just below the fuse box. This is visible when the plastic kickpanel is removed, which is required in the next step.

So all that's left is to run the blue brake wire from the wiring harness connector to the hitch.

[BigFoot48]

Task #5: Break control wire to hitch

A minimum 12 or 14 gauge wire is run from the Controller to the hitch. There are several panels that need to be removed or pried up to do this.

The drivers kick panel pulls out from the bottom.


Then the driver's step panel can be removed and the wire laid along the interior channel. Push under the plastic and carpet at the B pillar.


Here's the drivers step panel removed.


Here's the sliding door step panel pulled up for inserting the wire.


Continued below....

[Tim Vance]

Great post BigFoot!
Very clear and concise, great pics!

[box-E]

Nice write up!! I'd like todo this in the near future and talk my wife into a nice 16 or 17' Scamp or Casita. Drew

[BigFoot48]

Continuation....

Then the same for the sliding door.


For the rear section, I removed the spare tire cover and shoved the wire under the plastic until I could grab it and push it into the jack compartment.


So here's the jack compartment with the blue brake wire and a white wire that will be used to ground the hitch. See that box with the wires at the top? That's the Honda Control Unit for the hitch light connections. We'll follow its wires to get to the hitch.


The white wire is the ground and I added a connector and used the Control Unit screw to ground it. Rather fuzzy.


To get to the grommet to feed the brake and ground wire through, you have to open up the plastic that forms the bumper and sides of the car. On mine there are three screws on the edge of the plastic in the wheel well. Two of these hold on the splash guard. Remove these and you can pry the panel away to access this opening.

This is looking toward the rear after I fed the wires through. Open the larger grommet seen at the top of the picture to help in feeding the line. It's a bit tricky.
From here you just feed the wires down and along the bumper as shown in an earlier picture, connected to the hitch socket, and its all done!

[BigFoot48]

Reserved for showing all pictures...coming soon