No 12v when van hooked up to car

[Graham_374374066]

Hi,

tried out the van this week with a run to North Devon and 2 nights stay at a campsite.

Everything worked great and the car towed easily etc but on the way back accross Exmoor we stopped for a cuppa. My wife complained that the ignition on the cooker didn't work and I asked her if she had swithed on the 12v. She had but the guage didn't register (green/red batt condition) I puzzled for a minute then disconnected the van from the car - all now worked fine. Noticed when I reconnected the plug to the car that I can hear a relay click in the van. Came on home and checked the car electrics plug (13 pin euro) and is exactly as the diagramm, all other electrics work fine. What did I do wrong?

 

[xtrailman]

Do you have a selector switch marked car/caravan?

 

[vernon]

Was the car ignition 'Off', and pin 10 'dead'? if not the habitation relay will actuate and switch off all the 12 volts in the caravan.

This is probably what you could hear clicking when you reconnected.

 

[JTQ]

If its a modern van then is exactly what is design to happen.

A relay isolates all the services supplied by the caravans battery when the van is electrically coupled to the towing vehicle.

We simply unplug in lay-bys.

I assume its done to avoid the high alternator voltage damaging the vans electronics but as said that's my assumption.

Cheers John

 

[Graham_374374066]

thankyou for your replies.

Yes that sounds like it was the relay I heard. My diagram says pin 10 is the +ve supply to the fridge. I was worried that I had reversed the polarity somewhere and might have damaged the caravan system.

What it means tho is that I cannot use the car battery as backup for the leisure battery if I use a site with no hookup. I realise that it also means I cannot flatten the car battery.

thanks for your help once again.

 

[trucker]

Graham as I understand it the battery gets charged whilst travelling through the same pin as the fridge. (as told by Western Towing) the battery used to have its own pin on the 2x 7 pin system.

I havent used the 13 pin as yet as we are picking the van up tomarow but will not use it fully till march.

some reading of the manuals is in order me thinks

Kevin

 

[xtrailman]

I have looked at the wiring for the 13pin arrangment, on the CC site pdf download.

Pin 10 is a ignition controled supply.

But pin 9 is a permanent 12v supply for interior lights or caravan battery.

Pin 12 is the sensing device (relay)

If connected to ISO standard 11446

 

[Graham_374374066]

Thanks

so what should pin 12 be connected to on the car side? My wiring guide says 'coding(if req) normally spare'

Regards

 

[xtrailman]

Next thursday i have my towbar fitted and wired. I'll ask the fitter.

 

[vernon]

According to the wiring diagram in the 13 pin socket packet from Western Towing, pin 12 should be connected to pin 3 (lighting return) in the trailer, for trailer coding. This gives an earth return back to the car diagnostics via pin 12 when the trailer is connected, I linked mine, but I don't know if the car is connected to pin 12.

 

[Graham_374374066]

thanks

I assume ( as the van is new and already wired for europlug) that the van plug is already wired like that. I wired up the car myself (using two 7 core cables) and left pin 12 blank; hence my question about what to connect pin 12 to. I read the blurb on cc site tech leaflet but still no wiser.

Am content to disconnect in layby as suggested earlier but would feel more comfortable if I could be sure that the batt charges and fridge runs whilst we are on the road. We only ran for a couple of hours first time out and, of course, the battery was fully charged to start with. Only when I read the instructions for the fridge(on campsite) did I learn that I should have 'precooled' the fridge on mains or gas before I started!

 

[xtrailman]

One way to check if the car is charging the van battery.

The on board charger, only charges to around 13.5v.

The car will charge at around 14.7 volts.

Put a voltmeter across the battery.

 

[Graham_374374066]

magic thanks.

 

[xtrailman]

I had my towbar fitted today.

I asked the fitter, pin 12 i am told is unused.

pin 9, switches over to battery charging at 13.5 volts

The electricial did say that sometimes the car battery volts would sometimes stay high enough to still hold the relay in,(with the engine turned off), this is more common in some 4x4 such as a shogan with two batteries.

All the above is imformation, that i cannot personally cofirm.

 

[vernon]

Ray

Pin 9 should be a permanent 12v feed, and pin 10 should be 'Ignition switched 12v', which feeds the fridge and switches the charging relay in the caravan to charge the caravan battery.

Vernon

 

[Graham_374374066]

Ah maybe thats it, car battery at higher voltage so sensor in van still thinks it's charging. Will get the meter out when I next hook up.

many thanks for all your advice.

 

[xtrailman]

Vernon

The CC towbar wiring download, agrees with what the auto electrician told me.

Pin 9 is "Interior Lights etc or Caravan Battery Charging (Permanent Supply)"