Trailer connection for Jayco 12 Pin plug

[john_paul_128]

Hi All,

I wanted to post this diagram in hope that is useful to others wanting to connect a Jayco caravan with 12 pin flat plug to Discovery 4 12N/12S plugs. I can confirm that it works perfectly for my Jayco Expanda.

I am not an auto electrician and the diagram is based upon my own research and discussion with Jayco. Please use at your own risk!

My domestic fridge draws 12 amps and is well within the limits of the fridge wiring on the 12S plug, but if you have a much larger fridge this would need further consideration.

With thanks also to Colin Pedersen for his LED light digram posted on the site.

Rgds, John

[john_paul_128]

Hi All,

I wanted to post this diagram in hope that is useful to others wanting to connect a Jayco caravan with 12 pin flat plug to Discovery 4 12N/12S plugs. I can confirm that it works perfectly for my Jayco Expanda.

I am not an auto electrician and the diagram is based upon my own research and discussion with Jayco. Please use at your own risk!

My domestic fridge draws 12 amps and is well within the limits of the fridge wiring on the 12S plug, but if you have a much larger fridge this would need further consideration.

With thanks also to Colin Pedersen for his LED light digram posted on the site.

Rgds, John

There was an error in the original diagram - pls note updated version.

Rgds, John

[taffy]

Where did you get the 12 s Plugs

[rufusking]

Your diagram shows pins 5 & 7 going directly from the 12N to the flat plugs 5 & 7. As listed in the pin assignments at the bottom, 5 on the 12N is a tail light circuit but on the 12 flat is the brake controller wire.

I think it is pin 11 that has a assignment for the rear fogs (pin 2 on the 12 N) but this is very rarely used in AU.

I would bind both power circuit grounds (pins 3 & 7 on the 12S) to pin 10 rather than to the ground used by the lights (pin 3).

Might be worth moving this into the FAQ's after everyone has reviewed it.

[rufusking]

Where did you get the 12 s Plugs

Just check eBay, plastic or metal around $12 delivered. Make sue you search is set to worldwide.

12S 7-Pin Supplementry Towing Plug for Caravan electrics | eBay (http://www.ebay.com.au/itm/12S-7-Pin-Supplementry-Towing-Plug-for-Caravan-electrics-/190740722217?pt=UK_Trailers_Transporters_Parts&hash=item2c69087229&_uhb=1#ht_920wt_689)

[samandfee]

Hi Guys

Just to let you know john pauls plug set up works fine on our Jayco swan outback to Disco 4....great work.......

samandfee

[RickO]

Your diagram shows pins 5 & 7 going directly from the 12N to the flat plugs 5 & 7. As listed in the pin assignments at the bottom, 5 on the 12N is a tail light circuit but on the 12 flat is the brake controller wire.

I would bind both power circuit grounds (pins 3 & 7 on the 12S) to pin 10 rather than to the ground used by the lights (pin 3).


Hi rufsking / John,

Forgive what may be obvious questions but can I ask:

1. if you are identifying that that 12N pin6 needs to be wired to the 12 flat pin5?

2. why do you suggest that that 12 flat pin 10 be used - due to it being rated higher?

3. will a pulse buster be required if the 2014 Jayco Expanda van I have just ordered has LED tail lights?

Thanks a mil,
Rick

p.s. awesome work guys!!

[ADMIRAL]

[QUOTE=RickO;2162288]Hi rufsking / John,

Forgive what may be obvious questions but can I ask:

1. if you are identifying that that 12N pin6 needs to be wired to the 12 flat pin5?

2. why do you suggest that that 12 flat pin 10 be used - due to it being rated higher?

3. will a pulse buster be required if the 2014 Jayco Expanda van I have just ordered has LED tail lights?

Thanks a mil,

You don't need it for the LED lights, just the trailer tow functions.
Buy yourself one of the commercially available LED resistors ( Repco sell the Narva unit ) wire it between one of your indicator wires and earth on the van frame. The Disco will detect the circuit is correct at start up. The trailer icon will only come on when the indicator the resistor is wired to is selected, but don't worry. The trailer function has been selected, and it will all work correctly.

[tiddy]

Hi all, don't mean to hijack this, but some advice is needed, my wife & I have just purchased a MY14 Discovery & I will use the LR supplied hitch. I purchased a Hayman Reese tongue & ball etc, but I'm not sure what the two electrical connectors are for.

Can a standard box trailer be plugged straight nto the car?...as you can probably tell, towing, trailers & connectors is not up my alley.

Thanks for any help.

[rufusking]

Hi RickO,

1) Pin 6 on the 12N (Black plug) is for the brake lights, so yes it is needed and goes across to Pin 6 (NOT 5) on the 12 pin flat . Pin 5 is for the electric brake controller if fitted.

2) For the trailer lights there is an earth/ground at Pin 3 (12N and 12 flat). For the higher current loads the 12S provides two seperate grounds (Pins 3 and 7) but on the 12 flat there is provision for only one at Pin 10. All of the grounds go back to the same body stud behind the lefthand compartment in the cargo area.

Hope that helps and clears things up.

[rufusking]

Hi tiddy,

The two connectors above the towbar are for trailer and caravan lights and power. The white on on the left (passenger side) is refered to as the 12S and is used in the EU for caravans and the like. It provides battery direct and ignition controlled power (Pins 4 & 6) plus reverse.

The black one on the right is for trailer lights (brake, turn, tail). There is a minor difference to the AU convention in that the tail lights are provided seperately (left and right). If you do not have electric trailer brakes this is not an issue. If you do then when you turn on the tail lights (or headlights) power is feed to the pin that we use for trailer brakes and brings them on. Big problem. There are a number of threads and an proven solution.

Hope that helps.

[discotwinturbo]

Hi all, don't mean to hijack this, but some advice is needed, my wife & I have just purchased a MY14 Discovery & I will use the LR supplied hitch. I purchased a Hayman Reese tongue & ball etc, but I'm not sure what the two electrical connectors are for. Can a standard box trailer be plugged straight nto the car?...as you can probably tell, towing, trailers & connectors is not up my alley. Thanks for any help.

If the trailer has a large seven pin round you can plug it straight into the drivers side black fitting. Or if a small seven pin round, use a converter or change the plug on the trailer.

If trailer has led lights you may need a pulse buster installed, either permanent or temporary, or a resistor wired into one of the trailer turn indicators. Funnily enough I need this on most led trailers but my little box trailer with leds works without it.

Brett...

[discotwinturbo]

[QUOTE="rufusking;2162448"There is a minor difference to the AU convention in that the tail lights are provided seperately (left and right). If you do not have electric trailer brakes this is not an issue. If you do then when you turn on the tail lights (or headlights) power is feed to the pin that we use for trailer brakes and brings them on. Big problem.[/QUOTE]

I have read this before.

I installed my MY12 electrics brake controller myself, and always drive with my lights on, and never had an issue. I made no changes to the wiring for the trailer lights and brakes come on only when brakes are applied.

Does this only occur if you don't have a brake controller and have lights on while towing a trailer with electric brakes ?

Brett....

[rufusking]

Interesting, I also have a MY12 and the tail lights are split across two pins (5 and 7)
If you installed the electric trailer brakes the control wire for it must be connected to one of the pins and if it the standard assignment it would be Pin 5 on the black connector which would mean the right tail light was disconnected.

[discotwinturbo]

Interesting, I also have a MY12 and the tail lights are split across two pins (5 and 7) If you installed the electric trailer brakes the control wire for it must be connected to one of the pins and if it the standard assignment it would be Pin 5 on the black connector which would mean the right tail light was disconnected.

I can't recall the PIN numbers, but just ran the cable from the brake controller down to the 7 pin black into the appropriate pin to match the my trailer brake input, and that was it. All lights work fine.....paranoid about checking them each time. Brakes perfectly ok too (one trailer has 3 sets of brakes).

I didn't have any wiring that was different to my 4 trailers that I tow around....two of which have electric brakes.

Maybe I was lucky ?

Brett.....

[Meken]

I can't recall the PIN numbers, but just ran the cable from the brake controller down to the 7 pin black into the appropriate pin to match the my trailer brake input, and that was it. All lights work fine.....paranoid about checking them each time. Brakes perfectly ok too (one trailer has 3 sets of brakes).

I didn't have any wiring that was different to my 4 trailers that I tow around....two of which have electric brakes.

Maybe I was lucky ?

Brett.....


Did you cut the wire at the socket that you attached electric brake controller blue wire to (should be pin5 if your trailer electrics comply with Australian standards)?

[RickO]

Hi RickO,

1) Pin 6 on the 12N (Black plug) is for the brake lights, so yes it is needed and goes across to Pin 6 (NOT 5) on the 12 pin flat . Pin 5 is for the electric brake controller if fitted.

Just one more question if I may rufusking why would the electric breaks on the 12 pin flat be connected to the right side tail lamp on the 12N? Wouldn't this go to this be connected to the EBC?

Thanks,

[discotwinturbo]

Did you cut the wire at the socket that you attached electric brake controller blue wire to (should be pin5 if your trailer electrics comply with Australian standards)?

I will have a look on the weekend....it was about 2 1/2 years ago.

Brett....

[rufusking]

Just one more question if I may rufusking why would the electric breaks on the 12 pin flat be connected to the right side tail lamp on the 12N? Wouldn't this go to this be connected to the EBC?

Thanks,

We are not connecting it to the right side tail light, we are connecting it to the pin that the Europeans use for the right side tail light. If you are going to use the black plug (12N) then we disconnect / cut and seal the wire from the right side tail light and connect the EBC to the wire that goes into that pin.

If you are only going to use the flat 12 than you don't need to touch the right side tail light or the back of the 12N and just pick up all the feed from behind the left side light cluster / cargo are compartment and connectl to your new flat 12.

Clear?

[Nate]

Sent you a PM, any advice would be greatly appreciated.

[Stuzmiester69]

Thanks for putting up your wiring diagram John_Paul_128. I recently hired a van and towed it 4000 KM with my MY 2015 D4 with electrical connections on an adapter built from your post. Worked a treat. Perfect recognition of the trailer, green trailer light on the dash displayed with every indicator, reversing sensors turned off and car totally set up to tow the 2.5T monster on the back.

I did a lot of research before taking on the task and learned a few things that I thought were worth sharing. Hope you don't mind, but I have updated with my own wiring diagram, see attached. Welcome for anyone to make comment.

Things I can add are:

1. The 12N Pin 5 appears to come standard on the Disco as wired to the the RH tail lights. Unless you change this to an EBC output, the trailer brakes will lock on with a full 12V feed when your headlights come on. Could be really messy if you try and tow with the headlight switch on auto and you go through a tunnel or the sun drops behind a cloud or dusk comes around. Check Sneigy's post on the D3/4 Sticky zone on Electric Brake Controller Controller Installation - totally worth the 65 page slog to see some of the issues and get that one sorted out.

2. I love the flash buster circuit. Worked perfectly as stated above. Should work with either incandescent or LED trailer globes, so, if you are like me and you don't know what you are going to get when you hire a van, should work every time. Note the triple resistor arrangement = total resistance of about 6.3 Ohms = about the same as a standard 21W incandescent indicator globe. I got these from Jacar for almost nothing ('bout a dollar a pop). The three resistors combined are able to dissipate the heat well and I chose them after reading lots of stories about excessive heat coming of the Narva 21W single load resistor units. No issues on this circuit with heat.

3. The 12S plug - Only difference to the 12N plug is the male centre pin 7. I was running out of time to purchase a proper 12S plug off fleabay, so I just took a standard 12N plug and cut a longitudinal cut down the centre of the pin with a hacksaw, crimped the two halves toward each other (so the new pin fits inside the F pin 7 in the socket) with a pair of long nose pliers and hey presto -12N to 12S conversion - no waiting. Wrapped the outside of my creation in white electrical tape to identify which one plugs into which socket in the back of the Disco and all good.

Hope this helps anyone out there who is looking for a plug and play solution to wiring up without hacking apart their pride and joy (save for the ETBC, over to you Sneigy).

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