Electrical 7 pin wiring

[MarkAW]

Hi Folks

Just updated our Pajero to a new Prado.

Need to wire the new car for towing.....when we can get out.

From memory on the 7 pin I just ran a cable from main battery to pin 2 and 3 for trickle charge.

Existing pin 2 is reverse lights so I think I've previously just insulated and folded back and hooked in +ve from main battery.

For the earth in pin 3 I think I just spliced in the existing earth in pin 3 and ran from -ve battery terminal?

Is this correct to trickle charge.

Anderson plug for the fridge via VSR off the main battery.

I run a bcdc 1225d to aux battery so not running off that as it only puts out 25 amps and not sure it will keep at with 3 way in the van and fridge in back of the Prado.

Any thoughts if my memory is right?
Cheers

 

[mikerezny]

Hi,
I have attached the instructions for the Jayco 12-pin wiring. For the 7-pin, just ignore the heavy duty pins.

You are correct in that pin 2 is usually wired in a car to suppy reversing lights to a trailer. In a caravan, this pin is hijacked to supply 12V to the AUX input of the Setec or BmPro to supply 12V to the van if a van battery is not present, or to charge the van battery if one is installed.

take care
Mike

 

[MarkAW]

Hi,
I have attached the instructions for the Jayco 12-pin wiring. For the 7-pin, just ignore the heavy duty pins.

You are correct in that pin 2 is usually wired in a car to suppy reversing lights to a trailer. In a caravan, this pin is hijacked to supply 12V to the AUX input of the Setec or BmPro to supply 12V to the van if a van battery is not present, or to charge the van battery if one is installed.

take care
Mike

In the attached wiring diagram for pin 3 it states 'Connect to vehicle chassis ground point. Do not connect to trailer harness ground wire. Do not connect directly to negative battery terminal"

It was 4 years ago when i wired up previous vehicle. I think i spliced into the existing earth in the 7 pin and ran it back to negative terminal......i could be wrong but this clearly states not to.

So simply, i should remove trailer harness ground, insulate and fold back and connect my new negative to pin 3 and vehicle chassis earth?

Cheers

 

[mikerezny]

Hi,
I am not sure what is the trailer harness ground wire.

A vehicle chassis is as good as it gets for carrying current. In my FG Falcon, I found a convenient connection point on the main chassis not far from the trailer socket that was already being used to feed the earth to the rear light assemblies. I ran an earth wire from pin 3 back to that point.
I also ran the -ve wire for the fridge, pin 10 to the same chassis connection point.

Just to clarify, I used 8 B&S cable for the fridge wiring in the vehicle. 5m for the positive run from the socket to the tug battery and 2m for the negative run from the socket to the chassis.

My fridge draws 15A on 12v. When connected, the voltage drop across the positive run is 0.32V and the negative run is 0.07V.
The greater voltage drop on the positive run is due to the extra length AND voltage drops across the self resetting fuse and the ignition-controlled relay.

There is NO measurable voltage drop between the negative terminal of the battery via the chassis back to the earth connection.

When the fridge is running, the voltage difference between the car battery terminals and the 12V terminals at the fridge is 0.81V.
0.37V due to the car side: wiring, fuse, and relay and 0.44V in the standard Jayco van wiring.

take care
Mike

 

[Boots in Action]

Hi,
I am not sure what is the trailer harness ground wire.

A vehicle chassis is as good as it gets for carrying current. In my FG Falcon, I found a convenient connection point on the main chassis not far from the trailer socket that was already being used to feed the earth to the rear light assemblies. I ran an earth wire from pin 3 back to that point.
I also ran the -ve wire for the fridge, pin 10 to the same chassis connection point.

Just to clarify, I used 8 B&S cable for the fridge wiring in the vehicle. 5m for the positive run from the socket to the tug battery and 2m for the negative run from the socket to the chassis.

My fridge draws 15A on 12v. When connected, the voltage drop across the positive run is 0.32V and the negative run is 0.07V.
The greater voltage drop on the positive run is due to the extra length AND voltage drops across the self resetting fuse and the ignition-controlled relay.

There is NO measurable voltage drop between the negative terminal of the battery via the chassis back to the earth connection.

When the fridge is running, the voltage difference between the car battery terminals and the 12V terminals at the fridge is 0.81V.
0.37V due to the car side: wiring, fuse, and relay and 0.44V in the standard Jayco van wiring.

take care
Mike

Hi @mikerezny and @MarkAW , if you only have or use a SEVEN pin arrangement, terminal 3 (white wire) on vehicle SOCKET stays connected to vehicle chassis.
Terminal 3 (white wire) on van/trailer PLUG is the earth return for lines 1,2,4,5,6,and to 7 . I have never used pin 2 on vehicle or van to carry current to van as I have the separate lines to fridge by heavier cable and Anderson plugs.

If you use the TWELVE pin arrangement, there is no need for pin 3 on trailer/van plug as the heavier pin 10 on BOTH the vehicle and trailer provides the earth return for ALL circuits 1 to 9 and 11 and 12.
All earth return from van is transferred to vehicle chassis (not negative battery terminals) so as to avoid problems with "smart" alternators not being able to sense the electrical load and charge accordingly.

Personally, I like the idea of using a separate fused twin core line (with VSR in line) to Anderson plug at rear of tug, which is connected by Anderson plug on van direct to 3 way fridge. The earth return from fridge via Anderson plug is grounded to the vehicle chassis. I use separate cable (also fused and via same VSR) to terminal 8 at rear of tug which is connected to pin 8 on van plug. This provides max current/minimum resistance to Setec. I also upgraded the wiring for the earth return from pin 10 on both the van plug and the vehicle - heavier earth return to vehicle chassis. All other wiring is as per standard.

 

[mikerezny]

Hi @Boots in Action,
I am certain that, on my Penguin, the heavy duty wires on the large pins 9 and 10 of the 12-pin plug are wired directly to the 12V input terminals of the fridge.

I have just now checked, pin 3 (van Ground) is definitely NOT connected to pin 10 (fridge Ground).

take care
Mike

 

[Drover]

The standard 7 pin flat is wired as depicted, the reverse (pin2) is often used for low draw 12v supply to van or camera feed it was once often used for the breaksafe charge monitor in vehicle but isn't required in NSW anymore (orange wire) and I have used it to charge the Breaksafe.............. never change the other configurations or you will find dramas if you hook up other trailers....... vehicle earth is usually part of the wiring harnes for the vehicle but if you are sorting it yourself a good bolted bond on the chassis does the trick.... Before wiring up a 7 or 12pin to a new vehicle its advisable to check if a vehicle specific harness should be used as many light set ups are run via a canbus and connecting to them for a trailer/van lights will only cause codes to be thrown.....same as for van brake wiring, switches will often now only tell a Module to turn something on, so if you connect up to them theres no power to run things.....


Its always a good time to check the connections on the van plug as well, water does get into the cables and rot them out..... the wiring should be checked that its connected to the correct pins as well........ the earth in the van wiring is often earthed out at a number of points both on chassis and linked to the rest of the ground harness........... Jayco colour code is sometimes a mixture of european and australian so testing is important to save fuses.....

Narva | Trailer Plug Wiring Guide

A colour coded trailer plug wiring guide to help you require your plugs and sockets. Includes guides for 7 pin, 6pin, 5 pin, 12 pin, 13 pin, pin and heavy duty round plugs and sockets.

www.narva.com.au

 

[Boots in Action]

Hi @Boots in Action,
I am certain that, on my Penguin, the heavy duty wires on the large pins 9 and 10 of the 12-pin plug are wired directly to the 12V input terminals of the fridge.

I have just now checked, pin 3 (van Ground) is definitely NOT connected to pin 10 (fridge Ground).

take care
Mike

@mikerezny , that would be correct if not using separate lines to fridge with Anderson plugs. I originally had a 7 pin arrangement, but with separate wiring for fridge supply by Anderson plug.

 

[Boots in Action]

The standard 7 pin flat is wired as depicted, the reverse (pin2) is often used for low draw 12v supply to van or camera feed it was once often used for the breaksafe charge monitor in vehicle but isn't required in NSW anymore (orange wire) and I have used it to charge the Breaksafe.............. never change the other configurations or you will find dramas if you hook up other trailers....... vehicle earth is usually part of the wiring harnes for the vehicle but if you are sorting it yourself a good bolted bond on the chassis does the trick.... Before wiring up a 7 or 12pin to a new vehicle its advisable to check if a vehicle specific harness should be used as many light set ups are run via a canbus and connecting to them for a trailer/van lights will only cause codes to be thrown.....same as for van brake wiring, switches will often now only tell a Module to turn something on, so if you connect up to them theres no power to run things.....


Its always a good time to check the connections on the van plug as well, water does get into the cables and rot them out..... the wiring should be checked that its connected to the correct pins as well........ the earth in the van wiring is often earthed out at a number of points both on chassis and linked to the rest of the ground harness........... Jayco colour code is sometimes a mixture of european and australian so testing is important to save fuses.....


View attachment 67441

Narva | Trailer Plug Wiring Guide

A colour coded trailer plug wiring guide to help you require your plugs and sockets. Includes guides for 7 pin, 6pin, 5 pin, 12 pin, 13 pin, pin and heavy duty round plugs and sockets.

www.narva.com.au

Correct @Drover about not changing the other configurations. I also have a 6 X 4 trailer which has a 7 pin flat plug. Fortunately, the Baxters system I have fitted to tug (and van) means I can connect 7 pin flat plug on trailer directly to tug as the bottom 7 sockets accept the trailer plug perfectly and are even locked in by a connecting bar. The top heavier sockets are not used.
A good reminder about new car wiring and that it may not be suitable for van use - too light! And we all know about Jayco's colour coding in their circuits. Red is not always positive (can be white or another colour) and black is not always negative. Have seen it as the Positive line!!!

 

[Drover]

Fortunately, the Baxters system I have fitted to tug (and van) means I can connect 7 pin flat plug on trailer directly to tug as the bottom 7 sockets accept the trailer plug

Thats a thing with all 12/7 pin combo's, one of the few standardized things around.......... no matter who makes the things they will fit.........

 

[mikerezny]

Hi @Boots in Action,
what I am trying to get across is that one cannot use the fridge negative feed as a substitute for providing an earth for the rest of the van.

The fridge earth will not provide an earth for the rear lights, battery charging, etc.

The earth return for the van is provided via pin 3.

This is regardless of whether the fridge is connected to the car via the 12-pin terminals or a separate Anderson plug.

Consequently, your statement:
If you use the TWELVE pin arrangement, there is no need for pin 3 on trailer/van plug as the heavier pin 10 on BOTH the vehicle and trailer provides the earth return for ALL circuits 1 to 9 and 11 and 12.

is not correct. At least that is the case on my Penguin.

If pin 3 is not connected to the vehicle earth, the external lights will not work, nor will the van battery be charged from the vehicle.

take care
Mike

 

[Boots in Action]

Hi @Boots in Action,
what I am trying to get across is that one cannot use the fridge negative feed as a substitute for providing an earth for the rest of the van.

The fridge earth will not provide an earth for the rear lights, battery charging, etc.

The earth return for the van is provided via pin 3.

This is regardless of whether the fridge is connected to the car via the 12-pin terminals or a separate Anderson plug.

Consequently, your statement:
If you use the TWELVE pin arrangement, there is no need for pin 3 on trailer/van plug as the heavier pin 10 on BOTH the vehicle and trailer provides the earth return for ALL circuits 1 to 9 and 11 and 12.

is not correct. At least that is the case on my Penguin.

If pin 3 is not connected to the vehicle earth, the external lights will not work, nor will the van battery be charged from the vehicle.

take care
Mike

Correct Mike @mikerezny !! Well picked up. As my fridge is connected from tug to van fridge terminals by Anderson plugs directly with its own dedicated line, I do not have to use van pins 9 (auxiliary) and 10 (Earth return) . I used pins 8 (battery +ve ) and 10 (earth return) for battery charging line to Setec so do not have that problem. I overlooked that situation for those using those pins for fridge. Apologies.

But you are saying that your fridge terminals are connected to PINS 9 and 10 in van connector, which according to my Baxter's diagram is AUXILIARIES and EARTH RETURN respectively. So your fridge is using the pink line on pin 9 for power from tug?? and the earth return for fridge from pin 10 to tug chassis. That means that all your other van circuits 1,2 and 4 to 7 are all using earth return to tug via earth pin 3. Hence the need for earth line for that pin 3 separate from pin 10. And I guess that your line to Setec to charge battery is ORANGE from pin 8. But does van pin 9 get its power from tug auxiliary line and battery, or is the Auxiliary line connected to Battery +ve in van circuit?? If connected within van circuitry, then surely it must provide a suitable earth via Pin 10 for battery charging?? WOW!! That just about did my head in!!

Of course if all other loads on van are earthed to various different chassis points as @Drover mentioned, then there is NO proper earth return from van to tug chassis if heavy wire from tug to pin 9 is connected directly to the fridge terminals in van and the earth return from pin 10 on van is also only connected to tug chassis. So the van pin 3 on earth return IS the ONLY link back to tug chassis. (other than through the ball coupling or similar which is NOT satisfactory!!!) It would only work if a wire from somewhere on van earth chassis was spliced onto the return line from fridge or also connected onto pin 10 on van plug. I have not thought about what effect that would have on the van electrics. Different methods of making connections according to individual requirements. Now you have me thinking of any other eventualities that I have not considered.

 

[Drover]

On my 14.44 the small earth wire and the larger earth wire were coupled together in the birds nest under the van so all earths were on the same circuit, the 12v feeds also connected together so one 12v feed going to Setek and fridge, the Setek diode stopping reverse feed............... might depend on how much cable is left on the roll................................ Of course this didn;t last long as I soon changed it all....................... but it does show why you won't get a wiring diagram.....................

 

[Boots in Action]

Now that makes sense @Drover, as I wondered why there would need to be two different earth returns, one on van pin 3 which would be needed for 7 pin operation and on pin 10 (heavy) for 12 pin setup. Looks like there are heaps of ways to connect tug to van other than turn, brakes, stop and clearance lights which must be on their correct terminals. And I guess a lot would depend on wiring harness in tug too for the other connections.!

 

[Drover]

Now that makes sense @Drover, as I wondered why there would need to be two different earth returns, one on van pin 3 which would be needed for 7 pin operation and on pin 10 (heavy) for 12 pin setup. Looks like there are heaps of ways to connect tug to van other than turn, brakes, stop and clearance lights which must be on their correct terminals. And I guess a lot would depend on wiring harness in tug too for the other connections.!

I have found each needs to be run over with a meter as they are not all the same, the basic lights are okay but other stuff needs to be checked..... then you have the owner changing stuff ........ it does seem nowadays everyone is going for the seperate anderson run to fridge which is a good idea, though some fitters tend to make a heap of money by adding extra electonics so a simple inexpensive thing turns into a quite a few hundred dollars, cable, anderson, couple of connectors, a fridge switch is all that is needed.....

 

[Boots in Action]

I have found each needs to be run over with a meter as they are not all the same, the basic lights are okay but other stuff needs to be checked..... then you have the owner changing stuff ........ it does seem nowadays everyone is going for the seperate anderson run to fridge which is a good idea, though some fitters tend to make a heap of money by adding extra electonics so a simple inexpensive thing turns into a quite a few hundred dollars, cable, anderson, couple of connectors, a fridge switch is all that is needed.....

This Owner is guilty of "Owner changing stuff"! It is custom for connection of my 2011 Colorado tug to 2013 Jayco Penguin. When a new owner gets hold of my van, he will have to sort out my electrics and also the connections from his own tug.
@Drover , just a simple question. While underneath the van the other day, I noticed a bolted on earth connection to the van chassis (close to "birds nest"). The wire seemed to be coming from the multiple wiring inside a plastic cover protected by metal plate. Have not yet investigated but is this a prime earth point to van chassis for all circuits in van 12 volt and/or 240volt systems??? If so, then the earth pins 3 and 10 must have a connection to van for earthing purposes. But then, there would be some items that are NOT connected to any metal structural fixtures, just the timber frame or floor. I don't believe that my Setec is fixed to any metal body part other than the 240v lines, so it must rely on the earth return line to van connector to complete the circuit. Is there a wiring diagram for my van available just for interest sake???

 

[jazzeddie1234]

From what I've seen on mine the fridge earth is floating but the 7 pin extends through to the setec via the aux cable and to the brake wiring. The battery -ve has to go thru the shunt so I assume all devices use a return to the setec (or shunt). Mine also has a chassis earth further back which I assume is the 240v ground (but haven't confirmed).

 

[Drover]

I haven't found any wiring diagrams to date but I have noticed on various makes of vans a few earth points, that point your talking about I think I have come across similar where the ground from the 7/12 pin earths out and other van circuits run from it and there may be anpther grounding point elsewhere near whatever gizmo is doing the BMS ..... with the 240v chassis earth is often close to the mains breaker, of course this is earthing the chassis but the main 240v ground is the one in the cable....when you think about it, its surprising more folk haven't been zapped over the years....

I do know my fridge is grounded thru the van circuit as it has 12v from van battery for the board (withD+ off tug) while its 12v supply from the Jeep is earthed back to Jeep and is entirely indepenant but then I power my rear cam from the fridge tug supply so must have an earth, I could have fitted one, when cam drops off I know fridge has as well, usually anderson needs to be pushed in better......... its my warning system.... also when some idiot forgets to plug in after a stop (need to make a fridge switch relay for it)....

 

[mikerezny]

Hi,
I suspect we are all agreed on the following points. There is no 'standard' way Jaycos are wired. Either between different models and over the year of build. And probably who in the factory did the wiring.

I also suspect it will also depend on the type of fridge installed. A manual fridge needs only one 12V feed to power the heating element. This enables it to be wired completely independently of the rest of the 12v system.
On the other hand, an AES will have two, if not three separate 12V feeds: one for the heating element, one to power the fridge electronics, and a third sensing voltage (D+) to tell the fridge when to switch to 12V. In that case, one would need to carefully understand how the earth return works. I also suspect some dramas if the earth return for the heating element disappears and the element tries to return 15A via thin earth cabling originally intended to only power the fridge electronics and 12V sensing circuit.

Another consideration, we should easily agree on, is that all bets are off if the van has been modified from the factory, either by the present owner or previous owners.

So, on my 2016 Penguin fitted with a Setec ST20 series III. The aux input to charge the battery and to run the van off 12v if no battery is fitted is supplied from pin 2 of the 12-pin plug which is generally wired at the car end to provide power for the reversing lights.
The earth return for the Setec is wired to pin 3 of the 12-pin plug. On my Falcon, this runs directly to the chassis ground via a dedicated wire thick enough to handle the van external lights (all LED), the battery charging current (estimated at about 3A), and the electric brakes (max 6 Amps for a single axle).

On the Falcon, the earth return for the fridge is wired directly from pin 10 to the chassis ground.
I deliberately kept the two earth runs (pins 3 and 10) separate to avoid the voltage drop across the fridge earth (0.07V) from reducing the battery charging voltage since it is low enough as it is. In this case, it is being pedantic, but it adheres to the principle of good practice. Further, it was just too bloody hard trying to get the fridge cable into the terminal without trying to get an extra wire in there as well.

take care
Mike

 

[mikerezny]

But you are saying that your fridge terminals are connected to PINS 9 and 10 in van connector, which according to my Baxter's diagram is AUXILIARIES and EARTH RETURN respectively. So your fridge is using the pink line on pin 9 for power from tug?? and the earth return for fridge from pin 10 to tug chassis. That means that all your other van circuits 1,2 and 4 to 7 are all using earth return to tug via earth pin 3. Hence the need for earth line for that pin 3 separate from pin 10. And I guess that your line to Setec to charge battery is ORANGE from pin 8. But does van pin 9 get its power from tug auxiliary line and battery, or is the Auxiliary line connected to Battery +ve in van circuit?? If connected within van circuitry, then surely it must provide a suitable earth via Pin 10 for battery charging?? WOW!! That just about did my head in!!

Hi @Boots in Action,
all correct except:

Pin 8 is not used in the standard Jayco wiring. Refer to the pdf relating to 12-pin wiring that I posted earlier. This is exactly how my van came wired from the factory (and still is).

Pin 2 goes only to the Setec Aux in. From there, within the Setec it will charge the battery if fitted and supply 12V to power the van if a battery is not fitted (or if the battery isolation switch is inadvertently left off).
The original thinking at Jayco, when it was not common for a battery to be fitted to the van, was to enable the car to supply 12V to the van when off grid (stopping overnight on the way to a caravan park). So, pin 2 needed to be hot even when the engine was not running. Naturally, this was really only intended to power a light or two and light the stove. But that was way before 12V television, charging multiple phones and tablets, fans, fridge fans, etc became common.

Still a trick for new players with a van battery is to pull up for a quick overnight, leave the tug connected, leave the battery switch off, and bask in the warm glow of having a van full of 12V, only to discover the next morning that all that lovely 12V was coming courtesy of the car battery which now has insufficient charge left in it to start the car. I suppose, to be on the safe side, if a van battery is fitted, it would be prudent to disconnect the 12V plug to ensure the car battery is not discharging into the van. I don't bother, since 1: I know what I am doing, 2: our 12V usage at night is minimal, and 3: I will eventually live to regret making statement 1!!!! Although with lockdowns and the inability to even consider when we might go camping again, I would probably love to be in a position where my only worry was a flat car battery and no phone signal to ring the RACV.

Continuing:
There are only two wires on the heavy duty pins of the 12 pin plug, pin 9 for the fridge 12V, and pin 10 for the fridge ground.

take care
Mike