Technical Live cable hanging off in engine bay. 2004 Ducato 2.8 JTD

[archemedes]

You must have quite a big passenger seat as my Kontiki has 2 habitation batteries as well but only one under passenger seat and one under drivers.
Looks like the one under passenger seat is goosed as the terminal came off when I touched it and battery is flat. Not happy with wiring connectors on this as well. Looks like system needs a good check over. Its got a Solar Panel on the roof too and its turned off...

The drivers seat and the passengers seat are quite large on my Hymer. In the case of the passenger seat there is one habitation battery situated immediately underneath the seat and the other one immediately behind that battery in the well behind the seat.
In my case I've got a double free-standing solar panel (total 100 watts) that I only use occasionally. I considered having these mounted on the roof of the MH, but in the end decided to keep it as a free standing arrangement.
I must say that I'm not at all happy about the overall state of the wiring as it looks untidy and put together by an amateur.
Sadly none of this helps me as I've still got a live wire that doesn't appear to belong anywhere loose in the engine compartment.

 

[archemedes]

Remove the wire and forget about it.

If all the electrics are working as intended then it's most likely either something that a previous owner fitted and a subsequent owner removed but not fully or something the manufacturer fitted but was removed by a previous owner. because it was redundant Another possibility is just bad wiring, the wiring in my camper, while factory fitted looks like something an apprentice fitted on their first day at work, it's an untidy mess.

Believe me I have been tempted to tape the loose cable up and forget about it, but sods law being what it is I know instinctively that it will have a purpose, so I cannot do that.
I have quite a few options open to me at the moment which have been suggested on this forum, the first of which will be to try and establish if there should be a link between this cable and the habitation batteries.
The second option is to try and find out if it has anything to do with the horn that has stopped working.
Whilst I detest accepting failure, my last option would be to take the MH to an auto electrician and let them sort it out.
The problem with this sort of electrical enigma is to try and establish if the cable was originally put there by Fiat, or Hymer or as you say a previous owner.
I suspect that getting to the bottom of all this and fixing it is going the stuff that nightmares are made of.

 

[Torq]

It probably won't be as bad as you fear!

I forgot to comment on the horn problem. The connectors on the two wires to the horn are corroded and not making a circuit. Have fixed this a few times, road spray causes the corrosion. 20 mins, a bit of abrasive paper, some vaseline to protect the connectors and you'll be sorted.

 

[archemedes]

Here is the latest update.
The floating + cable in the engine bay is definitely not anything to do with the split charging as when the engine is running all batteries are charging at 14.5 v. When in a quiescent state all three batteries drop to different voltages, the starter battery to 12.5v and the two habitation batteries to 13.5v.
What I did discover was at some time in the past the battery inertia cut off switch which should sit on the top of the battery was completely missing and has been replaced by two in line fuses.
What I suspect has happened is that when 'whoever' performed this modification they neglected to remove one of the cables that had been connected to this unit because it was trapped behind the battery and not obvious and this is the mystery floating cable that has flummoxed me.
I have taped it up for the moment as everything on the vehicle works correctly apart from the horn which I suspect is the usual corrosion problem on the horn contacts.
I would like to thank everyone who has helped me for their support and very sound advice in getting to the bottom of this very perplexing problem.