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Discussion Starter · #1 · (Edited)
Hello everyone! Figured I'd finally get around to doing the trailer harness write up. This is a super easy install, and I had a couple small issues, and I figured out the solution so everything works 100%. The main problem was the main brake light wire, the wire used for the brakes. I tried to use this wire, only to find myself confused, and the lights not working at all like they should. After some trial and error, the main brake light wire is NOT needed. with the way the taillights are wired the brake and turn signal are the same light, and once I removed the brake light wire from the equation it worked flawlessly. On to the pics!

Ordered this harness from www.etrailer.com:



First I started to remove the rear flooring (held on by (4) 10mm nuts.



Then I removed the rear most trim piece (the one the hatch latches to)

After that I did not completely remove the side trim, just enough to be able to work around in there.


With the trim panels out of the way you can access the taillight plug and it is easily removable.

Next step is to test which light is which


For the sake of time, here is a picture of the correct ones so you don't have to hunt around for some help if you are by yourself. (This is a photo of the drivers side) The white and yellow wire is your tail light, and the yellow wire is the turn signal. THESE ARE THE ONLY TWO YOU WILL NEED TO TAP INTO ON THE DRIVER SIDE.


Once you are done with the driver's side it is time to move to the passenger side, and I did not get a pic, but IIRC it is a green and purple wire you tap into on that harness.


Here is a picture of the actual module, again THE RED WIRE IS NOT USED


In this picture you can see there the module is grounded


The positive connection is made here:



Module mounted:



Now just tuck the wire inside of the panel, and you're good to go!


And you can shut the hatch on the wire without damage. I was going to run it outside of the car, but I really did not want to drill a hole in the floor pan.


If you have any question feel free to post or message me!
 

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Mike:
This is just what I've been looking for! However, I couldn't read the part # on the package-could you provide it? Thanks!
 

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Discussion Starter · #4 ·

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thanks mike. i have a hopkins #46255 converter kit. probably the same just different wire color codes. you made my month.
 

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Thanks for the write-up, Mike. I trying to get up the nerve to use my Volt to tow my light-duty trailer in lieu of using a different car. What kind of hitch do you have installed? Did you install the hitch yourself?
 

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Thanks for the great write up. I attempted to install my wiring kit and ran into same issue with brake wire as you. Took it out of the loop and all is good.

I should mention that my 2011 Volt had different wire colors but same position. This didn't surprise me as my volt was also missing the factory nuts in the frame rail to bolt the curt hitch up.
 

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Very nice job with the photos. I always wince when I see scotch-lock wire taps being used though. I know it takes more skill to solder. Those taps damage the conductors (by design) and over time lead to problems due to corrosion.
 

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I was just looking for info on wiring in a trailer hitch harness and here this was. Thanks so much! BTW, what hitch did you use? I only see the Curt (fine product) available. This is the wiring harness that is powered by the battery, right? That is what I had to use on my Prius. Worked like a champ. But ... I do wish they had a plug in type like I used on my Kia Soul that was so simple to connect and did not require splicing or cutting wires.

Mike
 

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I have the Tork Lift invisi hitch.

I used Posi Taps for the cabling, no cutting required.
 

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You do not need an adapter to wire for a trailer on a volt. It is already a 2 wire system. That's why you didn't use the red wire. The red wire connects to a separate brake wire if the vehicle has a separate Brake wire. The adapter is for adapting a 3 wire system, with a separate brake wire, to a 2 wire trailer, where the brake and the turn signal are the same wire.
I have a 2015 Volt with a Curt hitch.
I wired my volt for a 2 wire trailer without an adapter, and it works perfect.
 

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The adapter is more for power isolation. I'd rather spend a few bucks on a powered adapter than have to replace my BCM because my trailer lights draw 10x as much current as the Volt's LED taillights.
 

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Hi Mike,
Just got a hitch on order from Carid.com, they had it (Curt) for 89 + 19 for shipping. Found the wiring harness on ebay (new) for 26 shipping included. I was wondering if you could tell me how to remove the side panels? What holds them in place? Too bad the light connectors cannot be accessed through those little covers! Have you pulled a trailer yet? Mine weighs 400 pounds empty. I think if I keep the load to 3 or 4 hundred (or less), it should be fine. Sure wish the other side (driver) frame rails were a mounting point. What would happen if the plastic panel underneath were NOT re-installed? Bad aero? Looks kinda like a big air scoop to me?

Anyway, thanks again for the write-up and the pics.

Mike B.
 

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isolation

The adapter is more for power isolation. I'd rather spend a few bucks on a powered adapter than have to replace my BCM because my trailer lights draw 10x as much current as the Volt's LED taillights.
What's a BCM?
Mine work fine without the adapter/isolator, but you can just replace the light bulbs on the trailer with led bulbs, and you can get them on ebay for a few dollars.
 

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There are two cargo hooks that have to be unscrewed and then it pulls off. Pull firmly and carefully. the back one comes off the same way, and there are no screws. I wired mine without an adapter, because there is nothing to adapt. The volt already has a two wire system, as do most trailers. You may want to put LED's in the trailer bulb sockets. I left the old ones in them.
The panel underneath is not too hard to reinstall, but you will have to cut some slots in it. I used a multi-tool that i got from Harbor Freight to cut the slots. It's the one with a vibrating blade on the front. makes it easy.
 

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What's a BCM?
Mine work fine without the adapter/isolator, but you can just replace the light bulbs on the trailer with led bulbs, and you can get them on ebay for a few dollars.
The Body Control Module is the computer that runs all the electrical accessories in the car, such as all the interior/exterior lights, horn, power windows, locks, etc. When you press the horn the switch sends a signal to the BCM, and the BCM closes a relay to sound the horn. The BCM has individual control of all the exterior lights, which is how it can light up only one corner of the car while programming the TPMS sensors. If the BCM is designed for ~1 amp of LEDs for a rear light, it may not take kindly to 10 amps worth of trailer lights being added.
 

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I installed the trailer wiring harness today, WHEW, what a job! I was afraid I would break a panel, so I pulled the light harness down carefully, and pulled out the little plastic inserts that hold it up on the inner fender. That gave me pretty good access on the driver side, but only a small amount of wire on the passenger side. You have to open the wire loom to get at the wires. I used the plastic snap connectors and they were difficult to attach while pulling down gently on the wires. When I got done, I realized that the very thin wires to the tail lights had not been cut into by the connectors. No big surprise, since they are only 20 gauge wire! So, had to cut, strip, twist and splice to get it to work. I ended up using a spade connector so that I could insert the hair-thin wires into the connector, then gave a good squeeze. The matching one went on the other wire and when put together, worked just fine. I did end up using a separate green wire from the right turn signal down through the panel to join the one from the module. The supplied wire is about 18 inches too short. Had to do the same for the drivers side, (remove connectors and cut and splice etc.),but all is well and the wires are tucked up and strapped in place. The hitch was delivered just as I was finishing up the wiring! Guess that will be my project for tomorrow. Hope it goes better than the wiring!! Thanks again for all the good info.

Mike
 

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Discussion Starter · #20 ·
Sorry I couldn't be of more help! I have not been on the forum in quite some time! Glad you got it all taken care of!
 
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