Electrical Time to replace 12-pin trailer plug and socket

[Jared01]

Hello,

I have a 2016 Jayco Starcraft Outback 17.58-3 in which the 12-pin plug on the caravan end as well as car end need replacing.

Looks like the below Narva parts will do the trick, unless there is something more heavy duty to consider using.

Caravan fridge (Thetford N504) is powered through the 12-pin plug and works well, although started to melt a little and wiring on caravan end started to corrode (photo attached).

Questions:
-Anything better to consider than the below Narva parts? If not, seems good enough to replace every several years if required.
-Is something like the below heatshrink wrap from Jaycar good to wrap around the wiring and onto the 12-pin plug to make it sealed with a heat gun?

12 Pin Flat Trailer Socket

www.narva.com.au

12 Pin Flat Trailer Plug

www.narva.com.au

Heatshrink Tape - Black | Jaycar Electronics

Ideal for emergency repairs or when you aren't able to use a piece of tubing. It conforms to odd shapes that heatshrink tubing is unable to.

www.jaycar.com.au

 

[jazzeddie1234]

I like the metal body version sold in supercheap for the towbar side as it is quite sturdy and uses plated pins. Not sure if there is any value in heat shrink unless the wires are a bit grotty. Many prefer running the fridge thru a separate anderson but I've had no issues with the 12 pin - although I check the pins often for dirt and the pin gap closing up

 

[mikerezny]

Carefully check the 12-pin socket on your car. Some vehicles use a reed switch mounted in the socket flap to deactivate the reversing sensors when a trailer is connected.If so, note that there are then two types of 12-pin sockets with reed switches: One that is open circuit when the flap is closed and one that is short circuit when the flap is closed. From memory, SCA used to have all three types in stock.

If you are replacing the plug and socket specifically because of the damage to the heavy duty pins supplying power to run the fridge, it might be a good time to consider leaving the existing plug and socket and supplying the fridge separately via a couple of Anderson plugs.

I have run the fridge for over 6 years using the heavy duty pins on the 12-pin plug and socket but have had to tighten the screws on the terminals for the fridge wiring a few times as they do come loose and the bad connection will generate enough heat to melt the plug and socket.
The pins also need opening up occasionally.
If the socket or plug was damaged from the fridge current, I would not hesitate to connect the fridge to the car using Anderson plugs.

 

[Boots in Action]

Hello,

I have a 2016 Jayco Starcraft Outback 17.58-3 in which the 12-pin plug on the caravan end as well as car end need replacing.

Looks like the below Narva parts will do the trick, unless there is something more heavy duty to consider using.

Caravan fridge (Thetford N504) is powered through the 12-pin plug and works well, although started to melt a little and wiring on caravan end started to corrode (photo attached).

Questions:
-Anything better to consider than the below Narva parts? If not, seems good enough to replace every several years if required.
-Is something like the below heatshrink wrap from Jaycar good to wrap around the wiring and onto the 12-pin plug to make it sealed with a heat gun?

12 Pin Flat Trailer Socket

www.narva.com.au

12 Pin Flat Trailer Plug

www.narva.com.au

Heatshrink Tape - Black | Jaycar Electronics

Ideal for emergency repairs or when you aren't able to use a piece of tubing. It conforms to odd shapes that heatshrink tubing is unable to.

www.jaycar.com.au

Hi @Jared01 , I think that the info/advice from @mikerezny is the way to go. My only advice is if you use the 12 pin flat (which I do) make sure that the 5 heavy duty pins are at the top . That way, the spring loaded socket cover on tug will lock down on top of and behind the thick plastic lugs on plug from van, thus preventing the cable dragging down on connectors, making them loose and causing heat build up , resulting in melted connectors.
As for heat shrink insulation, why not use heat shrink cabling?? It comes in various sizes to cover most situations and you only have to buy single strips of the sizing you want. Better than tape in my opinion and always tight too. Just noticed that the Narva specs for plug and socket is rated at only 15A. The Baxter brand I bought on Ebay were rated at 20A for the lower 7 pins and the upper 5 heavy pins were rated at 35A. All were brass pins also.

BAXTERS 12 PIN FLAT TRAILER PLUG & SOCKET CONNECTOR TRAILER CARAVAN CAMPER 4WD | eBay

BAXTERS 12 PIN TRAILER PLUG & SOCKET. 12 Month Genuine Warranty. PX Wholesales is 100% Australian owned and operated! MON – FRI - 8am - 5pm.

www.ebay.com.au

 

[Drover]

One of my kids turned up for the holidays with van (starnge I thought at first), fridge won't go Dad, 12 pin melted, so after I reminded him I said to chuck it when he bought it new, he said his van dealer said not needed, so I replaced it with a 7 pin and andersons, his 12 pin is mounted with the HD pins on top, so upsidedown from normal, this way the lead pulls down on the socket, forcing the smaller pins into the sockets and allows the HD pins to pull out slightly and if you don't check regularly that the pins are opened up then you end up with a meltdown, happened to me once on a vehicle which had the 12pin mounted that way and I have fixed a few similar............... He has a Thetford N 3000 fridge so when I checked the terminal at the back it also had a hot spot on the POS from tug, crappy spade fitting used by his Van Bloke.... Dad pointed out a few things to him, namely I'm speaking not from my bottom and next time he will be charged workshop rates..... Actually he went home with his 12v power anderson plugged into his new fridge anderson which I fitted and his van solar would charge his battery as I wasn't giving him my last anderson and a new 7 pin on van plugged into the tugs 12 pin because I only had a male 7 pin in spares box ...

Ideally chuck the 12 pin just use a 7 pin for the regular trailer lights and fit an anderson for the fridge and 12v van feed .... the 7 pin with andersons will give a few decades of trouble free life .................. I like to tin the ends of the wires before fitting and at the cable entry to plug if the cap has fell to bits I will wrap in some silicon tape or large heat shrink, if you seal everything up you just seal in moisture and it will corrode, better to have a loose lid/cap... wrapping the plugs up in a plastic bag when not in use is the worse thing to do as well.............................. 7 pin plugs come with proximity sensors if needed........

 

[Boots in Action]

One of my kids turned up for the holidays with van (starnge I thought at first), fridge won't go Dad, 12 pin melted, so after I reminded him I said to chuck it when he bought it new, he said his van dealer said not needed, so I replaced it with a 7 pin and andersons, his 12 pin is mounted with the HD pins on top, so upsidedown from normal, this way the lead pulls down on the socket, forcing the smaller pins into the sockets and allows the HD pins to pull out slightly and if you don't check regularly that the pins are opened up then you end up with a meltdown, happened to me once on a vehicle which had the 12pin mounted that way and I have fixed a few similar............... He has a Thetford N 3000 fridge so when I checked the terminal at the back it also had a hot spot on the POS from tug, crappy spade fitting used by his Van Bloke.... Dad pointed out a few things to him, namely I'm speaking not from my bottom and next time he will be charged workshop rates..... Actually he went home with his 12v power anderson plugged into his new fridge anderson which I fitted and his van solar would charge his battery as I wasn't giving him my last anderson and a new 7 pin on van plugged into the tugs 12 pin because I only had a male 7 pin in spares box ...

Ideally chuck the 12 pin just use a 7 pin for the regular trailer lights and fit an anderson for the fridge and 12v van feed .... the 7 pin with andersons will give a few decades of trouble free life .................. I like to tin the ends of the wires before fitting and at the cable entry to plug if the cap has fell to bits I will wrap in some silicon tape or large heat shrink, if you seal everything up you just seal in moisture and it will corrode, better to have a loose lid/cap... wrapping the plugs up in a plastic bag when not in use is the worse thing to do as well.............................. 7 pin plugs come with proximity sensors if needed........

Hi @Drover , the male pins on the 12 pin PLUG from van will NEVER pull down and loosen the connections with the 12 pin SOCKET on tug, PROVIDED THE SPRING LOADED COVER ON VAN PLUG LOCKS DOWN BEHIND THE LUG ON TOP OF SOCKET ON TUG. There is no movement possible!!
However, I will agree that if spring loaded cover is weak or non existent (broken off??) then the first pins to drag down and loosen will be the heavy duty 5 pins at the top. And yes, Andersons are the way to connect ALL heavy current wiring between tug and van.

 

[mikerezny]

I am NOT a fan of soldering the ends of copper wire if they are going into a terminal block. Especially if they will be carrying a reasonable current.

I did a specialist soldering course many, many years ago when I worked for Telecom Australia and it was drummed into us the negative aspects of doing this.
Yes, it does make the wire look nice and neat and tidy. And yes it may reduce the chances of the copper corroding.

BUT....

Point 1: solder is a metal much more malleable than copper. So, as soon as a solder coated wire is screwed down in a terminal block, the pressure from the screw is able to move the solder to REDUCE the tension on the wire. Ever seen a sparky running around in a house full of wiring soldering the ends of any wire going into a switch or GPO. In a whole house full of 240V wiring, not a single solder joint. 15A current through connections for many appliance plugged into GPOs. Up to 35A possibly on the switchboard connection feeding a string of GPOs. How many times do you get an electrician out to fix dodgy joints due to corrosion or loose terminals???

Point 2: Solder has a much lower melting point than copper. Take said soldered wired held into a terminal block. The solder moves due to the screw tension and the connection is not as secure. A small increase in resistance between the terminal screw and the cable results in some heat being generated. This heat, concentrated at the terminal connection is able to melt the solder allowing it to move away from the tension under the terminal screw, thus increasing the resistance and increasing the heat further. Eventually, enough heat is generated to melt the connector housing and possibly start a fire.

The above may probably be too technical. This is a shorter version.
DO NOT SOLDER COPPER WIRES THAT ARE GOING TO GO INTO A SCREWED TERMINAL BLOCK.

 

[Drover]

Yep @mikerezny was taught that as well, Navy had the same ideas along with crimping or soldering but have found in these situations it actually makes the connection last longer as the copper doesn't seem to corrode away just past the clamp point ..... my stuff is done both ways depending on the wire as well as laziness.... have seen some pro jobs where the wires have been crushed to death and totally useless, so it does depend on the operator as I imagine you have found as well... I quite like those little crimp sleeves you can get... firm grip and no cutting of wires.


@Boots in Action , if I had thought it important I would have had taken photos of the 12 pin plugs that have melted because of HD plugs on top, pins closed and movement, doesn't take much it seems to cause the problem............... my theory of pulling by the lead is just my assumption as every one I have come across is HD pins on top, haven't found a bottom meltdown yet, looking at the 12 pin Narva on my HiLux ute it is mounted upside down, the HD plugs are at the top, the flap is at the top and the NARVA logo is upside down, if it was mounted as designed the HD 's would be at the bottom and the flap as well as cable load would be holding them in place.................. its been recycled as the fridge pin is cooked, broke the 7 pin plug on it so put an old 12 pin in place as I just plug a 7 pin off boat into it and its happy....



An after thought what about marine cable ???????

 

[mikerezny]

@Drover , Copper and corrosive environments are not good companions. As you would certainly have experienced in your years in the Navy and now living near the sea. The main thing, where possible, is to keep the enclosing containers sealed from the atmosphere and moisture to reduce corrosion, cover the potential areas of corrosion with a protective layer (vaseline or some other protective goop), and inspect regularly to pick up any corrosion before it causes problems.

 

[Drover]

@mikerezny here we have corrosive dew nearly every morning, ideal environment to test things out ...................... have had gear that sat outside old shed for years no rust, here 3 weeks and covered in the stuff, now inside shed and sprayed with various concoctions to keep it at bay...... regular inspections a must on my boat and van....... but I have found a light tinning on wire ends, not a copious layer seems to work well, just like the marine cable can still see the individual strands....
If I solder the wires on anderson plugs then if there's a failure out bush I can disassemble and make a new cable using the same anderson something which I have had to do at times, even though crimping is supposed to make a less stress joint .......... I even made little push on caps for my sat dish sockets to keep the dew off them as they would start to corrode, we live a few kms from the sea so would hate to live on the beach ....
I leave my plugs reasonably open without adding any goop so things can drain and dry out, gone both ways with them and haven't found any difference which was a surprise... ants wanting to build a house is a problem.... might go back to a squirt of lannox.

 

[mikerezny]

@Drover I also solder the wires into the lugs on Anderson plugs. This is because the wire I use is so small there is no chance of crimping it, but mainly because I am a tight &^&^ I want to reuse the lugs! I also solder the wire on crimp terminals.
In both cases that is ok since the connection is not relying on the pressure of a screw to establish and maintain a good connection against the solder-coated wire.

 

[Boots in Action]

Yep @mikerezny was taught that as well, Navy had the same ideas along with crimping or soldering but have found in these situations it actually makes the connection last longer as the copper doesn't seem to corrode away just past the clamp point ..... my stuff is done both ways depending on the wire as well as laziness.... have seen some pro jobs where the wires have been crushed to death and totally useless, so it does depend on the operator as I imagine you have found as well... I quite like those little crimp sleeves you can get... firm grip and no cutting of wires.


@Boots in Action , if I had thought it important I would have had taken photos of the 12 pin plugs that have melted because of HD plugs on top, pins closed and movement, doesn't take much it seems to cause the problem............... my theory of pulling by the lead is just my assumption as every one I have come across is HD pins on top, haven't found a bottom meltdown yet, looking at the 12 pin Narva on my HiLux ute it is mounted upside down, the HD plugs are at the top, the flap is at the top and the NARVA logo is upside down, if it was mounted as designed the HD 's would be at the bottom and the flap as well as cable load would be holding them in place.................. its been recycled as the fridge pin is cooked, broke the 7 pin plug on it so put an old 12 pin in place as I just plug a 7 pin off boat into it and its happy....



An after thought what about marine cable ???????

Hey Ian @Drover, although I have been very pedantic about how the socket cover really does clamp the plug and connectors (all 12 of them) together, you have brought to my attention the (overlooked for me?) REAL reason that pins get hot and melt the plugs and sockets. I was totally ignoring the fact that even if the socket/plug are held tightly together and no movement at all, bent or loose fitting (closed) pins are only held in an "electrical connecting position" together by tight interference fitting. If not tight, then any movement of pins (even if socket/plug locked tightly together) and arcing will cause heat.
My Mrs Boots had difficulty separating the connections as not only does the locking flap have to be held up out of the way so plug can be removed, but there is also the drag of 12 pins being withdrawn from socket. After watching her unsuccessful attempts to disconnect plug from socket by vigorously yanking plug from side to side, I bravely stepped in and stopped this potential for damage to pins which would be helping close the pins. So, to keep the peace, I am told to "do it yourself"!! Might be a reason for not having had any problems - electrical anyway??

However, for some others, add in rough usage, dusty, dirty, wet or muddy connectors especially forcing plug into messy sockets and you have set the scene for a "hot" connection. I always make a check of both the socket and plug (even though both have spring loaded covers in good condition to protect the brass connectors) to make sure no contaminants will potentially cause heating/melting problems. As you said "pins closed and movement doesn't take much to cause the problem...and my theory of pulling by the lead" would seem to be correct and less about position of large pins.
Incidentally, I am sure you have seen your fair share of melted and badly fitted connectors, so I have no reason to doubt your observations.

 

[Drover]

Been there myself in regards to "Do it yourself", actually she begrudiingly stands at the back for light check and never ever guides me ................. (nearly running her over is her excuse but she didn't follow instructions) ................... I also had to go out to shed and inspect my only operating 12 pin plug just to confirm my "which side is up" view, I went for ages with no drama from a 12 pin while the flap opened down and the HD pins on the bottom, then with the Colorado the plug was up the other way, the HD pins on top and it wasn't long till melt down with the 14.44 in tow, I did a jury rig roadside as at the time I was running my rear view cam thru the 12 pin and the melt caused it to drop off which really saved a massive wire melding I reckon .... In camp I worked out it was the weight of the cable dragging things and closed pins from wrestling to pull apart, anyway, threw it in bin, pulled out the 7 pin from spares box, opened up the Lecky bag and with the LRPS humming away soldered up a new Anderson feed for fridge and 7 pins for the van, the cam was a temp job with spades until I got home where I fitted a 2 pin micro phone socket, the type I still use now ...............
Would have same problem in the semi, if the big round socket got wriggled too much sideways to unplug, the pins closed up and next time massive meltdown..... sat on side of road with a molten lump of plastic cutting the wires off and individually doing twist joins with tape, then taping the massive join to an okky strap so it wouldn't get pulled apart as I drove down the road ................. Spanner men back at base were most impressed with me that time ...... dumped another mongrel job on them............. or in the Snowy Mtns the things would ice up and short out........

On my own gear only one case of meltdowns but have fixed a few others, of course the rellies and visitors who I think only visit for maintenance work and a number in camps, folk then see the need for a soldering iron and genny............

 

[Boots in Action]

Been there myself in regards to "Do it yourself", actually she begrudiingly stands at the back for light check and never ever guides me ................. (nearly running her over is her excuse but she didn't follow instructions) ................... I also had to go out to shed and inspect my only operating 12 pin plug just to confirm my "which side is up" view, I went for ages with no drama from a 12 pin while the flap opened down and the HD pins on the bottom, then with the Colorado the plug was up the other way, the HD pins on top and it wasn't long till melt down with the 14.44 in tow, I did a jury rig roadside as at the time I was running my rear view cam thru the 12 pin and the melt caused it to drop off which really saved a massive wire melding I reckon .... In camp I worked out it was the weight of the cable dragging things and closed pins from wrestling to pull apart, anyway, threw it in bin, pulled out the 7 pin from spares box, opened up the Lecky bag and with the LRPS humming away soldered up a new Anderson feed for fridge and 7 pins for the van, the cam was a temp job with spades until I got home where I fitted a 2 pin micro phone socket, the type I still use now ...............
Would have same problem in the semi, if the big round socket got wriggled too much sideways to unplug, the pins closed up and next time massive meltdown..... sat on side of road with a molten lump of plastic cutting the wires off and individually doing twist joins with tape, then taping the massive join to an okky strap so it wouldn't get pulled apart as I drove down the road ................. Spanner men back at base were most impressed with me that time ...... dumped another mongrel job on them............. or in the Snowy Mtns the things would ice up and short out........

On my own gear only one case of meltdowns but have fixed a few others, of course the rellies and visitors who I think only visit for maintenance work and a number in camps, folk then see the need for a soldering iron and genny............

@Drover , I must have done something right at sometime, as I have the "best" reversing camera around - Mrs Boots!! No matter how difficult the angle or approach, "she who must be obeyed" is always able to direct me in tug to have the tow ball right under the hitch point without fuss or even speaking!! She stands just to the side of van opposite the tow hitch so that I can see her in the passenger side rear view mirror or in front of tug if necessary while I reverse. Then using the full and proper military signals of left/right arm out to turn (continue on that lock until she drops her arm or just by her side to continue straight) until signaled to halt when tow ball is close for a final check (then tug in park, hand brake on and foot on brake pedal - definitely whilst reversing - no moving between tug and hitch FOR SAFETY!!) . If coupling at suitable height and in line, the final direction is an indication of distance to go, once again provided by hand signal of amount to go by distance between palms of both hands. Never fails!!! And there is no yelling, screaming or swearing. And there is nothing like "happy wife, happy life" especially if they are in control!!! After that time there is nothing to argue about!
I have reminded her that it is the person directing the vehicle's driver who is responsible for any damage or problems, NOT the poor driver! Works for us.

Yes, I too remember the big NATO type coupling for connecting trailers to military vehicles, huge multi-pin things in a very heavy rubber cover and a very strong metal latching plate that locked into heavy rubber outer plug, usually on top, and never on bottom underneath. Those cables were heavy, probably the same on your semi??? One would need to be in a good mood and very patient connecting up the wiring which had been burnt out by just sitting at side of road and stripping/twist joining all the wires correctly. Amazing what you can do in an emergency!

PS. Mrs Boots is NOT for hire in directing tugs onto van couplings. her price would be much too high......... or I hope it would be!!!

 

[Drover]

I was meaning reversing the whole rig actually with The Bride some 14m behind but mostly that is in very tight spots as mirrors did it all otherwise, she will still stand well off to one side and wave stop.......... even with a 2 way she would forget to push the button or something, drive me nuts and don't dare laugh.
Hitching up before I had a cam on tug I would do it by myself, check height using my knee as a measure then line up with mirrors and use my truckie sense to know when to stop, which is really cunning if I didn't have a shadow I would lay a broom or stick on the ground as a hitch point guide sometimes get it first go others I would be an inch off don't recall smacking the bumper but have banged the hitch.......... even with a cam on van its mostly for when driving not so much reversing other than to make sure kids/dogs/wife not behind.

 

[Jared01]

Thanks for all the feedback.

I ended up buying the 12-pin Narva plug and sockets I linked in my original post.

The Narva 5 pins are good for 35a which is fine for my fridge.


I replaced the trailer end (plug) which all went well and took it for a trip over the long weekend.

Yet to do the car end, but have it ready when time permits.


Just bought some tape and sealed up the cabling to socket for now which looks good.

When I got caravan service quite some time ago, they had some sort of heat tape and wrapped it around and used a heat gun, which I might do some day.

 

[Drover]

I have actually not found any plug impervious to having a meltdown, just make sure the terminals are open each time you plug in, as Booties has mentioned the way they are unplugged ends up causing the pins to close up, loose pins means resistance and heat, hence meltdown, they are all 35amp and applies to all these plugs....
All these plugs will allow water in unless you bury in silastic, heat shrink over the end though does help keep water and dirt out..