Trailer connector wiring

[notlimah]

3 hours ago, leathermaneod said:

I guess I could but I don't really know how and I don't have the lights. Maybe I could just hook up and coil up a few feet of wire so it's "plug and play" if I ever want to add them? Would they need a seperate fuse though? Or just power from the reverse lights in that harness?

 

You could wire it up now and add lights later. I just got a pair of lights front tractor supply for 20-30 bucks and strapped them to the axles. It's in mikes write up and in my 'new truck' thread. Just splice into the reverse light wire and then run a relay if you want a switch to be able to control on and off with a switch.

[flagmanruss]

I built an extension harness for my 79 Chevy C30...  It would plug into the bumper connector & thread under the tailgate inito the truck bed. 

I reused the harness, I used a hole cutter to clearance he bedliner on the Dodge & then installed the FM plug in the bed wall behind the rear axle.  I had to cut the ears off the M plug to feed it through the hole in the bed wall.  The harness in now secured along the frame & the M plug is baggied & rides on top of my trailer package F plug under the bumper.  It avoided making any cuts in the OEM wiring.  & worked perfectly.     

 

In recent years, I use solder & heat shrink tubing for trailer wiring.  I don't want to be re-doing it EVER! 

Edited September 10, 2016 by flagmanruss

[01cummins4ever]

I prefer the UN-insulated seamless butt connectors, and add the heat shrink my self, they give a strong and secure connection and no 2nd guessing if you got a secure connection or not, My local napa usually has them,

Ive learned by working on heavy class 8 trucks and trailers that not only good connections but proper wire securing is a must, have a lot of zip ties on hand

Like w & F says your factory gauge wire size should be sufficient,

 

try these

https://www.napaonline.com/napa/en/p/GRO843101/GRO843101

 

[notlimah]

My dad is one of the most anal people I know when it comes to do anything 'the right way' he won't do any wiring unless he can solder and heat shrink it himself and I've never seen any of his work fail.

[IBMobile]

8 hours ago, leathermaneod said:

I just don't know what size it is on the truck and thought maybe someone here would lol it's not all the same size either. 

This is the wire for a factory Trailer Tow Connector

 

    FUCTION                    GAUGE       COLOR

1  ground                            12               black

2  trailer brake                    12               light blue

3  tail/running lights            14               black/orange

4  12v power/charging        12               red/orange

5  left turn/stop light            16               dark green/red

6  right turn/stop light          16               brown/red

7 back up                            18               violet/black         

 

[leathermaneod]

47 minutes ago, IBMobile said:

This is the wire for a factory Trailer Tow Connector

 

    FUCTION                    GAUGE       COLOR

1  ground                            12               black

2  trailer brake                    12               light blue

3  tail/running lights            14               black/orange

4  12v power/charging        12               red/orange

5  left turn/stop light            16               dark green/red

6  right turn/stop light          16               brown/red

7 back up                            18               violet/black         

 

Thanks for that. Really kinda sucks though because I just got done doing it all with 14 awg  it didn't seem like there was anything bigger than that. Guess I need to go get some 12 awg and redo the ones that are 12. Can't win. 

[dripley]

Just thinking out loud, but if those 12 gauge wires fit in the 14 gauged but connector I dont think it is going to hurt any thing. I cant believe there is that much difference between the tow except for diameter off the hole you put the wires in. I am sure someone will correct me if I am wrong.

[IBMobile]

A 12 gauge wire will not fit into a 16-14 gauge butt connector (color coded blue).  The 12 gauge wire will only fit into the 12-10 gauge butt connector (color coded yellow).  I've had experience with this when I ran out of yellow butt connectors and tried to use the blue. 

[dripley]

19 minutes ago, IBMobile said:

A 12 gauge wire will not fit into a 16-14 gauge butt connector (color coded blue).  The 12 gauge wire will only fit into the 12-10 gauge butt connector (color coded yellow).  I've had experience with this when I ran out of yellow butt connectors and tried to use the blue. 

just assuming here but if the wire fits the connector he should be good providing all the strands go in.

[01cummins4ever]

The 12 gauge wire will fit only if you force it to fit. Thier is a reason for the 12 gauge wires that the battery charge, brakes and ground carry more load than the rest of them

 

[leathermaneod]

Hey guys I got the job done alright :-) Thanks for all the tips! Interestingly enough, none of my wires seems to be as big as 12 awg. I was going to redo the 3 big ones with 12, but my friend and I carefully compared the trucks wiring to the 14 gauge I had bought and they were the same. Also compared the sizes with the wire stripper and the trucks wires were perfectly stripped with the 14 gauge hole as were the wires that I bought. I seemed to have 4 that were 14, 2 16, and 1 18. Maybe OEM wiring is just smaller even though they call it a certain gauge? Or maybe autozones wire is just big? Who knows, but we decided against redoing anything as it would not have been necessary. The 12 gauge I bought was very clearly much bigger than anything on the truck. Yes I know bigger is is not bad, but it wasn't worth all that extra work and wasting material to redo things. I didnt have a lot of time to waste on this project either. 

 

Some pics of my work

incase you are wondering, I did splice in an extra set of wires to go up to a connector in the bed for my future gooseneck hauling. That's why there are two wires on the one side. I just cut off all the factory wiring at the scotch locks, and added my own from there. Since I didn't have easy access to the crimp/solder/hear shrink connectors that you guys showed me, I made my own version by removing the plastic from a regular crimp connector, crimping it, soldering it, coating it with dielectric grease because I didn't have adhesive lined heat shrink, and then heat shrinking. I think it worked out well and I now have a harness that looks factory. To save money i used all black wires and made labels with a label maker. Btw that white wire I was asking about, it's powered with the brake lights. I assume it would be for wiring in a third brake light so that it doesn't blink with the turn signals. The only thing I would do differently looking back is clean some of the wires on the truck before soldering. The smaller gauge ones had kind of a black oxidation on them when the insulation was stripped. I tried to clean it off with brake cleaner but it didn't work so I just crimped, then soldered the best I could. The heat and flux seemed to help remove it and I'm sure I got a good enough connection, but if I had thought of it at the time, I would have used some steel wool or scotch brite to clean them a bit. I can try to get a pick of the finished product tomorrow if anyone wants. Btw I pulled a trailer today and it all works lol

[IBMobile]

13 minutes ago, leathermaneod said:

Btw I pulled a trailer today and it all works lol

That's all you can ask for.  With the crimp and solder connections covered with grease an heat shrink I think you'll be ok.  If you find out you are drawing heavy amp load on one of the wires you can always run another wire.

[notlimah]

As long as it lasts and works that's all you can ask for! Nice job.

[leathermaneod]

I forgot before but I wanted to ask you guys, should the 12v power to the trailer be energized all the time? Even with the key off? Because it is....lol

[01cummins4ever]

With key off I would say no, you might do some digging to see if someone hot wired it somewhere, it should be protected by a fuse

if it were hot all the time and you had s RV hooked up that would lead to dead batteries on your truck if left sitting for any lengthy of time.

[Wild and Free]

The 12V+ power supply is battery power and hot all the time on all trailer plugs so it is correct.

Can't tell you how many fuses I have blown when accidentally touching 2 terminals together in the trailer plugs over the years trying to troubleshoot things due to the constant "Hot" 12V+.

[leathermaneod]

Thank you both for the replies! @01cummins4ever, that is exactly what I thought, but apparently we are wrong! Thank you @Wild and Free for confirming this! I don't think I blew a fuse, but I tried to cut multiple wires to the same length and got a small spark! I was shocked because the key was off. Why is it designed this way?? Is there something built in to prevent batteries from being drained by a trailer?

[Me78569]

You and me both wild and free.  I keep a few of those fuses as spares.

[leathermaneod]

you guys don't happen to know off the top of your head which fuses they are?

[01cummins4ever]

If yours is set up that way , the only way to prevent battery discharge is to unplug the trailer if left hooked up for any length of time.

That's only if the trailer you are hooked to utilizes the 12 v circuit 

my 12v circuit goes off with key off, so I don't know what the factory spec is on that one