# 12 volt not disabled when engine starts



## Foxtrot (Jul 26, 2007)

Hi,
Any suggestions as to why my 12 volt system does not disable when engine starts, it always did.
My MH is an Autotrail Cheiftan 2007.
I have unplugged Sargent controller above door to reset & checked all fuses in EM50 & EC325 Sargent controller.
Still having problem with Omnistor step randomly operating.

Regards Doug


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## Glandwr (Jun 12, 2006)

How would a 3 way fridge work if the 12v system was disabled when driving?
Ours is always on unless we isolate it manually.

Dick


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## 100127 (Jul 20, 2006)

The 12 volt side of the fridge is independent from the leisure 12 volt, as it works directly from the vehicle alternator.


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## GEMMY (Jun 19, 2006)

If the 12v supply ceased, then how would some people operate their slow clookers via an inverter whilst on the move :wink: 

tony


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## 100127 (Jul 20, 2006)

Agreed Tony, but inverters should be wired directly to the leisure battery. On my Starefire the 12 volt system worked whilst the engine was running, but on my Tracker it doesn't. Strange :roll: :roll: 

Bob


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## Glandwr (Jun 12, 2006)

Full 12v system has always been live in our van. I can't see the benefit in it not being, but can see some for it being.

Why would you design it so that it goes off when you turn the key?  

Dick


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## Glandwr (Jun 12, 2006)

Does it mean that you have no lighting in the hab. area when on the move?

Dick


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## 100127 (Jul 20, 2006)

Glandwr said:


> Does it mean that you have no lighting in the hab. area when on the move?
> 
> Dick


No idea, will let you know when I next try it.


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## GEMMY (Jun 19, 2006)

It's a British vans peculiarity :wink: 

tony


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## csmcqueen (May 12, 2010)

Glandwr said:


> Does it mean that you have no lighting in the hab. area when on the move?
> 
> Dick


All British manufacturers have to/do disable (A regulation I believe) the hab electrics when the engine is running. No Lights, power etc except to fridge which is taken direct from base vehicle electrics when engine is running.

Me, I located the relay that controlled it and put in a switch to 'allow override' :wink:

Scott


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## csmcqueen (May 12, 2010)

Foxtrot said:


> Hi,
> Any suggestions as to why my 12 volt system does not disable when engine starts, it always did.
> My MH is an Autotrail Cheiftan 2007.
> I have unplugged Sargent controller above door to reset & checked all fuses in EM50 & EC325 Sargent controller.
> ...


If its not disabling the rear electrics then check if the leisure battery is charging when the engine as running as it may be the 5amp 'D+' fuse in the door pillar that's blown.

This is the control wire that Peugeot/Fiat/Citreon put in so that motorhome manufactures can detect a feed from the split charger. A lot of British manufacturers also use this to trip a relay to cut out the hab electrics.

urbanracer kindly put this image up for me:










Its just 2 screws on mine so hopefully the same on yours.

Scott


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## Fatalhud (Mar 3, 2006)

The random operation of your step & the non working of the hab cut out could be linked
On my 2004 bessecarr (sargent system) there are 2 split charge relays
1 does the charging of leisure battery, the other gives 12volt to fridge, signal to auto close step & signal to cut Habitation 12v (red / yellow cable)

Although my van is an earlier version of sargent, the way of woring may be the same

I actually did not like the cutting of the habitation, so i cut it out of the system by breaking into the red/yellow cable as it goes into the sargent PSU

Alan H


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## Fatalhud (Mar 3, 2006)

Although these are Swift drawing they may be similar, so hope they help


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## Glandwr (Jun 12, 2006)

csmcqueen said:


> Glandwr said:
> 
> 
> > Does it mean that you have no lighting in the hab. area when on the move?
> ...


Would I be right in thinking it a regulation designed for caravans that has just been extended without thought to motorhomes. Or is there a logic?

Dick (apologies Doug for going off topic)


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## Penquin (Oct 15, 2007)

For MH (and caravans) manufactured in the UK the standards are imposed by the National Caravan Council as to what is an "acceptable" build.

The NCC rules lay down that the 12v system in the rear of a MH or a caravan must be disconnected when the engine is running. So that applies to ALL UK manufactured vehicles.

Not of course Hymers, Rapidos, and other "foreign" vehicles.

It can be disabled so that the 12v does stay on but......

for us with a UK manufactured Swift, the 12v goes off totally in the back, the fridge circuit is of course totally separate and is controlled by a relay so that the 12v can only be supplied to the fridge when the engine is running.

The only other circuit that is activated when the engine is on is the charging to the leisure battery of course......

The NCC rules to me seem totally illogical but they write them and of course, the clue is in the name National CARAVAN Council - of course no-one should be travelling in a caravan when it is being towed (it is illegal I believe).

Dave


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## menis (Jul 9, 2010)

*12v Not working*

Hi Doug,

With regards to your step problem, I have what sounds like the same issue - it will not extend fully or retract fully unless we either pull firmly when extending or push firmly when retracting. Having seen other posts on this forum, I contacted my dealer who advised that it sounded like a faulty 'poly-fuse' and that for me at least that would be resolved under my warranty if I took the van back. My dealer is near Newcastle but Sargent Electrical are in Beverley - much nearer to me - so I asked the dealer if they thought Sargent would help. He said thought Sargent were a great company and may well help. I 'phoned Sargent who also said the 'poly-fuse' was the likely cause and I've just booked my van in with them for next week.
I would suggest you give them a call on 01482 678981 and ask their advice about both the step and the 12v question.
Top marks to Tyne Valley (my dealer) and Sargent for their support.
Menis


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## holeshole (Mar 20, 2010)

The Sargent website gives schematic diagrams for the vans for which they manufacture the looms, see http://sargentshop.co.uk/epages/esh...ories/TechData/"System Schematics"/Auto-Trail

They are very helpful in all the dealings I have had with them.


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## Foxtrot (Jul 26, 2007)

Thanks to everyone for their helpful replies, I will start to look into the various possibilities.


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## Foxtrot (Jul 26, 2007)

Thanks to everyone for their helpful replies, I will start to look into the various possibilities.


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## Foxtrot (Jul 26, 2007)

Further update,
I took the cover off the door pillar, no fuses just a couple of large plugs with loads of wires, all seem to be connected OK.
Also followed link to Sargent wiring diags, these do not show the full setup as the system is controlled via EM50 black box & EC325 controller.
Could not find any reference to a "poly fuse" but will give Sargent a ring.
Again many thanks.


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