routing a trailer wiring harness outside the trunk

[atebit]

I have a 2007 Sedan & I am planning on installing a Class I hidden hitch to tow a (very light) trailer. I'm trying to figure out a way to route the wires from the taillight controller out of the trunk and underneath the car to come out on the rear driver's side. I had a look at the underside & no grommets or anything jumped out at me that looked like an easy way to do this...any suggestions?

[atebit]

Originally Posted by atebit

I have a 2007 Sedan & I am planning on installing a Class I hidden hitch to tow a (very light) trailer. I'm trying to figure out a way to route the wires from the taillight controller out of the trunk and underneath the car to come out on the rear driver's side. I had a look at the underside & no grommets or anything jumped out at me that looked like an easy way to do this...any suggestions?

Actually found a nice size grommet right under the spare...don't know why I didn't look there sooner...

[pcosens]

Originally Posted by atebit

. . . route the wires from the taillight controller . . .

Just curious which controller you used, are you happy w/ the performance of the unit?

Paul

[atebit]

I used this one that I purchased at redtrailers.com:

http://www.redtrailers.com/ShowItem.asp?id=31823

There were no instructions with the unit...the leads that had to be connected to the electical system were all marked as to their function on the unit, and follow the "industry standard" color code for trailer light functions as far as I could tell. So all I needed to know was what color Yaris wire did which function going into the tail light assemblies.

The excellent wiring diagrams provided by Mustang made that a snap. I just unsnapped the rear carpeting covering the tail lights (which I needed to do anyway at some point to install my cargo net), and located the appropriate wires on the left and right side, based on the wiring diagram. The controller comes with "vampire"-style taps that allow you to connect the controller wires to the Yaris wiring without cutting anything.

Mustang's wiring diagram shows which side drives the center-mounted stop light (I can't remember if it's the left or right side now). I selected the other side to connect the brake light lead from the controller, reasoning that the side driving the center-mount stop light had enough to do already. This particular controller draws power for the trailer lights directly from the Yaris tail lights themselves (you're basically wiring the trailer lights in parallel with the Yaris lights).

Some more expensive controllers require a direct connection to the battery, and just use the Yaris tail light voltages as "soft switches" to drive the trailer tail lights directly from the battery. I don't have that many lights on my trailer that drawing the extra current through the tail light wiring would be a problem as far as I was concerend.

There was actually another gromet I found that was a little more convinient to use, since it wasn't under the spare tire. I saw it after I removed the carpeting from the tail lights. The trailer connector end is already attached to the controller, and it wouldn't fit through the grommet, so I cut the the trailer side of the wiring and just routed the wires through a hole I poked in the grommet. That's when I figured out what the butt connectors were for that came with the controller. I used the butt connectors to re-attach the wires I had routed back up through the gromet back to the controller. I tried to cut the wire so the butt connectors stayed inside the trunk, which left plenty of wire to route the trailer connector near my hitch, so I could pull it out and attach to the trailer when necessary.

So all in all I am happy with the controller. It did come with one of those neon light tester things that are supposed to light up when you ground one end and touch the prove to 12VDC. However, the one they sent my was not working. I would suggest using a good voltmeter over one of those things when testing your work anyway.

[ctrj]

I'm curious--
How much of a trailer are you pulling and how does the Yaris do pulling it? Could you post a picture of the car and trailer?

[atebit]

Originally Posted by ctrj

I'm curious--
How much of a trailer are you pulling and how does the Yaris do pulling it? Could you post a picture of the car and trailer?

It is a fold-up 4'x8' trailer that I bought as a kit from redtrailers.com.

The trailer itself as purchased is just a frame. I added a 4'x8' piece of plywood (cut in half to allow the trailer to fold) for a floor. I also built side panels from another piece of plywood and cut-up 2'x4's for stakes.

So far I've only used it a few times. Once was to go about 400 miles down the east coast on the highway, with the trailer holding boxes of light houehold goods. I could definetly tell the engine was under a heavier load pulling the trailer, but once I got up to speed on the highway, it was fine. Just like pulling any trailer, you need to be mindful of breaking issues/stopping distances. Stopping distance was definetly increased, but a little testiing before I got on the road helped me get comfortable with that.

The other time I used it was to bring some trees/shurbs home from a local nursery. I also had a few bags of stone and other gardening items in there as well. There were a few more steep hills on this trip, and while the Yaris was straining a bit to get up some of the hills with the trailer, it ended up geting the job done. Again, the heavier the trailer, the more you have to watch your stopping distances.

Since Toyota recommends you don't use the Yaris for towing, I don't endorse this or recommend you try it for yourself; I can only comment on my own experience so far. I really added the trailer hitch to the Yaris just to connect my bike rack; towing the trailer was more of an experiment for me. I have a more powerful vehcile that I'd use for towing a serious load.