Wiring trailer lights

[dat_sun720]

Having a very hard time to figure out how to wire in a 4pin flat connecter to my 81' 720. The part I can't figure out is the brake light since it's connected to the left and right signal on the connecter. 

[datzenmike]

The 720 share the brake and turn signal so that is not going to work.

 

On the 6 wire round plug at the right rear of the 720 box near the tail lights, the Green/Black wire provides a stop and a right turn signal. The Green/Red wire provides a stop and a left turn signal. 

 

Knowing this you can run wires from the Green/Black stripe to the right side signal/brake trailer lamp(s) and a wire from the Green/Red stripe to the left side signal/brake trailer lamp(s).

 

On the 6 wire plug.....

 

Black is ground

Red/Yellow is the 'running lights' and license light when headlights are on.

[NC85ST]

They used to make converters for doing this. I don’t know if they still do, it’s been 20 years since I last wired one.

[Charlie69]

Here is an ebay link for a 1980-85  Nissan 720 trailer wiring converter kit.

https://www.ebay.com/itm/184592714623?var=0&mkevt=1&mkcid=1&mkrid=711-53200-19255-0&campid=5338590836&toolid=10044&customid=417d6215249514b9d6370183ac834e34

[flyerdan]

You should be able to get 5 to 4 converter boxes at marine or trailer supply places for way less.  I got some from iBoats years ago, just looked they're out of stock but should be available somewhere.

 

[Stoffregen Motorsports]

Most auto parts stores carry those converters. They cost like $20.

[iceman510]

 I think I have one from my old hardbody if interested.  I will send it for cost of mailing.

 

 

[bottomwatcher]

Yeah the 5 wire converter is available but make sure you make proper connections either soldering them yourself using liquid electric tape or shrink insulator. Those stupid "vampire" clips that come with trailer wiring are garbage shit rigging. Also the trailer wiring itself clean grounds and a jumper on break frames are essential.

[Stinky]

I later had brake-light problems, so you may not want to listen to me.  I believe that I have a short under the seat that caused all of my problems.

 

I spliced in to the wires 1'-2' away from the rear taillight.  Not sure that that was wrong.  You should have a license plate light wire in the center of the truck, near the bumper.  I cut the wires, and used a high temperature connector splicing the 2 wire ends and the trailer connector in to one and then put shrink wrap over it....and then electrical tape.

 

I think that there are 4 wires going in to each corner, ground, tail, turn, brake.  The brake and signal wire come together near the bulb socket.  Your PU has the brake and turn light on the same circuit/filament.   Your trailer is probably gonna be similar.  At first, I only had one turn signal (which flashed on both sides).  But ,I have since changed that as it confused the heck outa my tow dolly.

[Goemon]

This will have one more set of wires added to make a plug in trailer light harness for the 620
I got the rear end of the seat to rear harness and the end of the taillight harness. 
This will plug in between the  2 harnesses so there are no butchered wires
Find a 720 in a junk yard and make you one.

[Goemon]

This will have one more set of wires added to make a plug in trailer light harness for the 620
I got the rear end of the seat to rear harness and the front end of the taillight harness. 
This will plug in between the  2 harnesses so there are no butchered wires
Find a 720 in a junk yard and make you one.

pic

Edited December 29, 2022 by Goemon

[flyerdan]

Where you're going 2 into 1, be sure and put some diodes in line so you won't backfeed into the other circuits.

[bottomwatcher]

And buy one of those led trailer plug testers. It takes the guessing out whether it is the truck or the trailer that is the no light issue. I have a bunch of trailers and keep a brand new harness and set of lights at the house. If I have light issues and the lights are more than a few years old after cleaning all connections still have a problem I swap the harness first if and if no joy then the lights and I am back on the road. I use the led sealed units that are non serviceable and they never last as long as they claim. 

[wayno]

This does not make sense to me, 1980 thru 1982 have an amber lens for turn signals, the brake lights are stand alone and share the bulb with the running lights.

But one needs a dedicated ground wire also, so it would need a 5 prong connector, 6 prong if you have trailer brakes.

[Goemon]