# What trailer wiring harness?



## APCruze (Mar 7, 2013)

This might help you a little, I when I put the trim model in it shows the Curt one fitting and the the other one not, but it does say for the Cruze, so not sure why its doing that, 

http://www.cruzetalk.com/forum/12-w...w-cruze-trailer-wiring-cheap-alternative.html


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## sciphi (Aug 26, 2011)

The only difference between the other adapters and that one is the $50 ones are powered separately from the vehicle taillights. I am planning on running LED trailer lights, so the power draw should be minimal.

EDIT: According to Curt's Website, the $45 one is not powered independently while the more expensive one is powered independently. I'll save my money and wire up to the taillights myself. LED's don't draw that much power.


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## Sunline Fan (Jul 29, 2012)

I have the Curt one and it is powered from the tail lights. Remove the harness that plugs into each light and plug the harness in line on each one. There's a converter box in line to convert the separate turn signal feed into the single bulb trailer system. It's a 15 min install.

I think the conversion of the turn signal feed is where you'd have troubles making a harness yourself.


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## NickD (Dec 10, 2011)

With my DeVille history, elected to buy a hidden trailer hitch for my 88 Supra, never thought I would do this.

Same problem as the Cruze, separate directional and brake lights. Most trailers use a combination brake and directional bulb. So why not make the trailer like the car. For three bucks each mounted to more tail lights on the rear of my utility trailer.

Wires are one one ground, one for tail lights, one for brake lights, and two more for the left and right directionals, adds up to five wires. Standard connector is four, so added the fifth with a spade connector on it. Two outside lights are red for brakes, right next to them are amber for directional's. 

So far no problems with the law, how can they argue since they make cars this way? And beats those Made In China POS adapters that don't last very long.


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## sciphi (Aug 26, 2011)

Sunline, how does the Curt one work with regular trailer lights? If it's fine with regular bulbs, I should be okay with the Harbor Freight LED trailer taillights I purchased.


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## Sunline Fan (Jul 29, 2012)

sciphi said:


> Sunline, how does the Curt one work with regular trailer lights? If it's fine with regular bulbs, I should be okay with the Harbor Freight LED trailer taillights I purchased.


Yep, no problems with traditional lights. I've only used the harness for my freshly restored boat trailer so far, and all was well. It doesn't have any amber clearance lights, but the tails are running lights. One is a dual filament and then other has two separate bulbs, so one is essentially a running light bulb. Aside from some light fixture/bulb issues at first, it all worked perfect.

Supposedly there's a place to run the harness down through a hole and outside, but I just keep mine in the spare tire area and drape it out of the trunk when I need if. Plenty of wire, and this way it stays clean. 

In light of the Cruze wet spare tire wells, I'd recommend covering your plug and storing it on top of the tire so it doesn't get wet/short out.

I have a pic for you but the wonderful AG app won't let me upload it.


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## NickD (Dec 10, 2011)

Here is a DIY circuit using two relays, four diodes, and two capacitors. Bottom bulbs are your trailer lights.

When you hit the brakes, both trailer bulbs will ignite. With just the turn signals on, that relay will switch the trailer bulb to the turn signal voltage and will flash in sync with the vehicle. That capacitor has to be sized to keep that relay energized during the off period of the turn signals. So even if you hit the brakes, that trailer bulb will still flash.

The advantage of this relay circuit is that the trailer bulb is seeing full battery voltage in either the brake or turn signal mode. These cheap solid state versions have a substantial internal voltage drop greatly dimming the bulb. Have taken several of these back. Opening one, looked like a five year old kid put it together. Learned later, Made in China, a five year old kid did do the soldering. And use way undersized components.


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## Sunline Fan (Jul 29, 2012)

Here's the pic Sciphi:


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## sciphi (Aug 26, 2011)

Thanks!

I ordered the Curt wiring harness, since plug and play works well for me. I will need to store it somewhere in the trunk, as I have no spare tire, just the can of goo. 

OT: The Curt hitch is a nicely-built piece! Mine came in today, and it's tank-like in construction. I also approve of the installation method, since it will not compromise my rust-proofing that much.


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## NickD (Dec 10, 2011)

sciphi said:


> Thanks!
> 
> I ordered the Curt wiring harness, since plug and play works well for me. I will need to store it somewhere in the trunk, as I have no spare tire, just the can of goo.
> 
> OT: The Curt hitch is a nicely-built piece! Mine came in today, and it's tank-like in construction. I also approve of the installation method, since it will not compromise my rust-proofing that much.


Have only compliments for Curt Mfg. Co., located in Eau Claire, WI, USA. Contacted their engineering department to find a hitch for my Supra. Emailed me blue prints of what they thought would fit. Fit perfectly, heavily plated, and gave me a darn good price.

After miserable luck with Made in China stuff, nothing like dealing with a US company again.


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## Sunline Fan (Jul 29, 2012)

sciphi said:


> Thanks!
> 
> I ordered the Curt wiring harness, since plug and play works well for me. I will need to store it somewhere in the trunk, as I have no spare tire, just the can of goo.
> 
> OT: The Curt hitch is a nicely-built piece! Mine came in today, and it's tank-like in construction. I also approve of the installation method, since it will not compromise my rust-proofing that much.


You can hide most of the harness behind the plastic trim piece right inside the trunk, but storing the rest shouldn't be too bad. Just bundle it up and tie it around itself or get a twist tie.

Agreed on the hitch, that's what I have too. It looks cleaner than the Draw Tite counterpart and is quite durable. I've had my ~3k pontoon boat on there, which nearly bottomed out the rear suspension, and it was solid. You really feel when a trailer hits a bump though, it'll pull the car back a little.



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## NickD (Dec 10, 2011)

Sunline Fan said:


> You can hide most of the harness behind the plastic trim piece right inside the trunk, but storing the rest shouldn't be too bad. Just bundle it up and tie it around itself or get a twist tie.
> 
> Agreed on the hitch, that's what I have too. It looks cleaner than the Draw Tite counterpart and is quite durable. I've had my ~3k pontoon boat on there, which nearly bottomed out the rear suspension, and it was solid. You really feel when a trailer hits a bump though, it'll pull the car back a little.
> 
> ...


Pulling a 3,000 pound boat with a Cruze? Ha, made a deal with my son, I got a 3,000 pound boat, he got an SUV with a class III hitch on it.

Kicked this around with the Cruze, only good for a class I hitch for pulling my utility trailer, built on an old boat trailer. Didn't want to buy an SUV, so using the Supra for these occasional hauls that can handle a class II hitch. Motorhome has a class III hitch, but really don't want to try to back up a utility trailer with this. 

Thought about using the motorhome for the boat, and even have a spare hitch to mount on the front bumper for launching and loading the boat. Maybe one of these days. 

Always doing building projects, wife suggested getting a Silverado. What good would that do? Can't even lay a 4 by 8' sheet in these darn things. What is GM thinking? But selling a lot of these things for people that have need for power on the road with nothing back there. But it takes them a half a day to park these things a Walmart.


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## sciphi (Aug 26, 2011)

Thanks for the advice! 

For hauling my little 4x8 trailer, this setup will work just fine.


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## NickD (Dec 10, 2011)

It does bring about a question of trailer hitch rating, assume for highway use. But if you live on the other side of the street to lake shore property where the same home and property taxes are 1/3 as less. And only have to drive your boat a block or two to a public launch at walking speed. Wouldn't think it makes much difference, as long as your vehicle can pull it out.

In our case, 14 miles, even though the law doesn't require it, installed electric brakes on our trailer. If people see you are pulling a large boat, just love to pull out in front of you. Same with a motorhome, on this, installed 150 db horns.


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## sciphi (Aug 26, 2011)

I ordered the Curt 50125, or so I thought. What showed up was the powered Curt 50214, or the one I wanted all along! Yay! It means more installation work to run the power wire to the battery from the trunk. That's nothing new for a Cruze, though. The upside is that this unit is only using the taillight wiring for signals, and not to power the trailer lights! Brighter trailer lights are always a positive for me.


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## Sunline Fan (Jul 29, 2012)

NickD said:


> Pulling a 3,000 pound boat with a Cruze? Ha, made a deal with my son, I got a 3,000 pound boat, he got an SUV with a class III hitch on it.
> 
> Kicked this around with the Cruze, only good for a class I hitch for pulling my utility trailer, built on an old boat trailer. Didn't want to buy an SUV, so using the Supra for these occasional hauls that can handle a class II hitch. Motorhome has a class III hitch, but really don't want to try to back up a utility trailer with this.


It was more an exercise to prove to myself that it could do it, and was just around the block. I definitely knew it was back there, but never panicked. Not sure I'd want to try pulling it out of the water on a ramp with it, but all in all not bad. The biggest issue was not being able to see around it.



sciphi said:


> I ordered the Curt 50125, or so I thought. What showed up was the powered Curt 50214, or the one I wanted all along! Yay! It means more installation work to run the power wire to the battery from the trunk. That's nothing new for a Cruze, though. The upside is that this unit is only using the taillight wiring for signals, and not to power the trailer lights! Brighter trailer lights are always a positive for me.


Hmm, what's the price difference? Did they charge you for the 50214 instead?


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## MN_Falcon (Jul 7, 2014)

sciphi said:


> I ordered the Curt 50125, or so I thought. What showed up was the powered Curt 50214, or the one I wanted all along! Yay! It means more installation work to run the power wire to the battery from the trunk. That's nothing new for a Cruze, though. The upside is that this unit is only using the taillight wiring for signals, and not to power the trailer lights! Brighter trailer lights are always a positive for me.


Sorry to post here first -- I was just doing some searching to see how people were installing the power wire for the Curt harness. Here is the deal on the Curt wiring for the Cruze. Last fall I bought a hitch and the non-powered 56125. After install I tested all of the combinations of brake lights and signal lights. I was testing with the car running. I found that signals worked properly alone but when the brakes are applied and a signal is turned on the light barely flickered. I emailed Curt and worked with a fellow -I probably should not put his name on the forum- that went through all the different tests that he would like to see, since most problems end up being ground issues. He ended up sending me out a second unit and it seemed to work properly, but I was testing with the engine off. A few days later I hooked up the trailer and ran out to pickup a snow thrower that was given to me. In the snow I cold tell that the signal was barely flickering again when the brakes were applied. I contacted the fellow at Curt again and he got the techs to bring in a Cruze so that they could do some testing. Here is the content of the email that the tech guy sent back to me:

"**** here is the email from engineering, it has to do with the duty cycle of the signal when the vehicle is running and not running. 
We investigated a 2014 Chevy Cruze LT1 today (a 2013 was not available).

The vehicle functions as a normal 3-wire system when the vehicle is off but when the vehicle is turned on a 75% duty cycle 100Hz PWM pulse appears on the stop wire (see attached). This pulse causes our 56125 product containing our M27 board to work incorrectly when the brakes and signal circuits are applied at the same time.
Our M224 boards built after 1/16/2013 have an additional feature that filters out these types of pulses on the stop wire.

To fix this issue we will have to modify our 56125 to become a powered application using an M224 board."

So to anyone else with the non-powered 56125 unit you may want to double check, with the engine running have someone step on the brake and turn on either signal light. If the trailer light is more or less constant brake with a little flicker off then back on again, you will likely be seeing the problem described by the Curt techs. the newer power unit does fix this issue.


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