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Towing - Trailer wiring 7-pin

22K views 10 replies 4 participants last post by  buckerbie 
#1 ·
I know this is a fairly well worn topic but I was wondering how some of you wired a brake controller for trailer brakes into the Mo. I have the OEM hitch and wiring harness but wanted to swap the 4-pin harness out for a 7-pin so that I could have a trailer with electric brakes.

I took the Mo to several RV and trailer shops last year and several of them mentioned that no one makes an aftermarket wiring harness for the brake controller or for the 7-pin. Two of the shops even pulled out the Draw-Tite parts book to show me that under "Nissan Murano" it clearly states "See Nissan Dealer" instead of part #s. They also shared a Service Bulletin from Draw-Tite that stated that they should NOT work on the Murano's because a large number of incidents have been reported where the MOs had some rather expensive electrical issues after the aftermarket wiring was installed.
 
#2 ·
Hey, thanks for asking. I'm also curious, as I have been thinking of "upgrading" to a 7-pin as well. Didn't realize it would be such a big deal...

Has anyone done it?
 
#3 ·
If you already have the 4-wire connector at the back for your trailer; you can just cut the connector off and buy a round 7-pin connector and reconnect the 4 wires you have then add and run a black 12v wire; white ground wire; red aux. wire and the blue brake wire from the 7-pin connector to the car.
I've attached a diagram for the location of the wires.
 

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#5 ·

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#6 ·
Wiring?

Just curious, most trailers under 3500 lbs, don't have elec brakes, so why have the controller? The Nissans with towing cabability greater than 3500 lbs have either the entire controller harness built in or have the plug there for a harness. I'd be concerned about cutting into the harness.
 
#7 ·
Re: Wiring?

H cheese said:
Just curious, most trailers under 3500 lbs, don't have elec brakes, so why have the controller? The Nissans with towing cabability greater than 3500 lbs have either the entire controller harness built in or have the plug there for a harness. I'd be concerned about cutting into the harness.
The towing capacity of the MO is 3500 gross. Electric brakes on any trailer is not a bad thing.

Trailers come with options for electric brakes for any size. Brakes on trailers are truly mandated by different States and Provinces. North Carolina requires trailers with GW over 1000 lbs to have brakes.

Here's a listing for brake laws: http://www.cerka.ca/catalog/trailer_size.asp
 
#8 ·
Brakes

Oh, thanks for the info. I know here that anything over 2500 need brakes, but most of them are surge brakes. I just had not seen elec brakes of trailers that small. Brakes on a 1000 lb trailer seems like overkill to say the least, does some legistator own a brake company? Just kidding..

I pull a 6000 lb travel trailer with my Titan, so I'm very well aquainted with controllers, hitches, etc. But it doesn't make me a expert.
 
#9 ·
My brother's pop-up tent trailer has brakes, and it comes in at about 2500lbs. Some boat trailers (with total weight coming in under 3500lbs) also have brakes (not many, but some do).

I'd like to just have the option. Given a 7-pin connection, then all the various adapters for other connections, seems the best solution. If I can get that hooked up without too much trouble, I'd like to have it.
 
#10 ·
It should be an easy installation. The connection I purchased is a 6-pin unit so that I can run 12v power to my cargo trailer(it doesn't have brakes) for powering lights without needing to run the car and having the lights on.
The 4-wire unit really has no power running through it with the car turned off and if you don't step on the brake pedal so cutting it at the connector isn't an issue.
Once you do cut it off; adding a 6 or 7 pin connector is as easy as stripping 1/2" of wire and inserting it into it's proper hole and tighten with the set-screw for that wire.
Then you will need to run your blue electric brake wire from your modulating unit(in the car) to it's home on the connector.
You will also need to start a black 12v wire (from either a hot line or the battery-good starting point with a dedicated fuse) to the connector.
The last red wire is for aux. use(I guess it can be hot too).
What ever you decide to do at the car-end; you can always get an adapter to meet your trailer needs.
The website I attached eariler has lots of info. They are a local trailer builder and parts supplier for trailer builders around here.
Have a look; worth the info;)
 
#11 ·
In California, the RV dealers are required to install brakes for any trailer with a GVWR of 1500lbs or more. Typically they choose to install electric brakes over surge brakes since most buyers prefer the controls of the electric brakes. I ended up buying an older tent trailer (1994) with a dry weight of 1000lbs and GVWR of 1395lbs. So legally, I can tow this trailer in CA without any issues.

However, I had to sacrifice a lot of features and options to find a lightweight older trailer. All new tent trailer today, have a GVWR of over 1500lbs.

From a safety standpoint, it still worries me some not to have the trailer brakes. I'm headed back up to the Pacific Northwest this summer with the tent trailer and will cover nearly 2500 miles with some good sized mountain passes in both California and Southern Oregon. I drive slow and leave plenty of space in front of me but if I had to make an emergency stop if someone cuts me off, my total GCVWR (total weight of MO, trailer, passengers, and cargo) is pretty high and would take me a while to stop especially on a 7% downhill grade at freeway speeds.

Normally to install a brake controller, the manufacturers tell you to tap into the brake pedal switch wiring. This still concerns me since I would be splicing into the the MOs electrical. I wonder if it would still work if I tapped into the brake light wire in the 4 pin connector? Isn't that the same thing? The brake controller would still receive a signal when the brake is depressed.
 
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