Urgent Help, Tow Bar Electrics.

Discussion in 'Motorhome Chat' started by haganap, Aug 4, 2012.

  1. haganap

    haganap Funster Life Member

    Joined:
    Dec 5, 2007
    Messages:
    11,065
    Likes Received:
    13,667
    Location:
    Heavan
    Ok, where to start, here's a story, please read on. If it's not sorted soon, look for me at the nearest bridge, my head is offically cod and battered.

    I purchased a tow bar and electrics from a friend of mine dedicated to fit my van. It was working when it came off so I had no reason to doubt its working now.

    I installed it on the van which consists of doing the following, Unplugging 1 cable, leaving 2 scotch type connections, these are then pluged in to the new loom made for the swift van. Then locating a plug near to where the towball is fitted un plugging it and plugging the new one in. Then there is two plugs in to the westfalia box and a relay.
    this = job done. other than connecting the earth strap.

    So I done all this and plugged my tail board in, and no lights of any sort. All the lights on the motorhome work as they should do.

    It was then suggested that maybe there was a fuse gone in the van? I therefore checked every fuse loacted this side or manchester and checked it, still no working. Then, I spoke to the seller of the towbar whom insisted it was working but happened to have a complete loom and westfalia box as a spare so I could check a few things out. all that plugged in and same problem.

    So moving on, I had a good think about it and plugged the old loom back in so i could return the new one. I then disconnected the earth on the chasis that comes with the towing electrics and checked at the socket with my multi meter. I placed a prong in the earth of the plug socket, and probed the other pins, all of them showed live when I turned the van electrics on with hazzard lights. I then completed the same process at the tailboard lights and again showed power at the bulbs. However, when I then touched the earth cable to the chassis, the power seemed to dissapear ? giving no reading at teh towing socket, release the earth and power comes again?

    I plugged the car in to be sure it was no the tail board and when plugged in, one indicator flashes on the car but nothing else, and then it's debateable as to what happens in the car electrics next.


    My thoughts are that there must be an earth fault? is it because I have been unable to secure an appropriate earth with the earth strap? Even though I can rub it hard on the chasis to no evail, and why does the power die when I touch the earth on to the chasis?


    Any ideas would be helpful, even simple ones, to ensure that I have considered simpe things
     
  2. bungy

    bungy Funster

    Joined:
    Jan 24, 2010
    Messages:
    2,246
    Likes Received:
    4,127
    Location:
    Welsh marches
    Hi Paul

    Have you tried any Resistance checks - just to check for any shorts between any of the pins?

    with the power disconnected obviously!!
     
  3. old-mo

    old-mo Funster Extra Special Life Member

    Joined:
    Oct 16, 2008
    Messages:
    12,715
    Likes Received:
    38,569
    Location:
    Dorset
  4. haganap

    haganap Funster Life Member

    Joined:
    Dec 5, 2007
    Messages:
    11,065
    Likes Received:
    13,667
    Location:
    Heavan
    Hi mo, thanks, they are factory looms. There is no wiring involved at all. I have two looms, the new one and the one that came off, same on both:Sad:
     
  5. acting_strange

    acting_strange

    Joined:
    May 16, 2010
    Messages:
    3,398
    Likes Received:
    2,568
    Location:
    North Hykeham
    OK....take ALL of the board bulbs out and run the checks again..then replace the bulbs one at a time until the fault comes back...

    I did once find that some idiot had put the wrong type of bulb in a fitting and this shorted the system to earth...
     
  6. andyman

    andyman Read Only Funster

    Joined:
    Sep 23, 2007
    Messages:
    1,133
    Likes Received:
    489
    Location:
    Leicestershire
    Sounds like a missing power supply. On both my Saab and Bmw I used a dedicated loom but still need a supply from the battery.
     
  7. TheBig1

    TheBig1 Funster Life Member

    Joined:
    Nov 27, 2011
    Messages:
    7,206
    Likes Received:
    9,588
    Location:
    Dorset
    dont forget your connecting to a can bus system. I agree that there is a live feed from the battery missing. as for the light board, that sounds like a bad earth if only one bulb works on a known good vehicle
     
  8. haganap

    haganap Funster Life Member

    Joined:
    Dec 5, 2007
    Messages:
    11,065
    Likes Received:
    13,667
    Location:
    Heavan
    as I said Andy, there is power at the plug, there is even power at the trailer board. until I hook up the Earth Lead.

    These systems are simple and sirt of fookl proof, you unplug three plugs, plug in 3 plugs and jobs done. :Angry:
     
  9. TheBig1

    TheBig1 Funster Life Member

    Joined:
    Nov 27, 2011
    Messages:
    7,206
    Likes Received:
    9,588
    Location:
    Dorset
    the last can bus towbar wiring kit I used had a 12v+ve to the battery as well. the system will show power without from the vehicle harness but not enough current to power the lights on the trailer. connecting the earth will complete the circuit and the body control module cuts power to the circuit thinking its a fault
     
  10. bungy

    bungy Funster

    Joined:
    Jan 24, 2010
    Messages:
    2,246
    Likes Received:
    4,127
    Location:
    Welsh marches
    electrickery always takes the path of least resistance...are there any points in the system where you can do the good old half split method, by checking on the loom itself with it disconnected by doing a beep test with the meter
    connect one probe on a pin on one and and then the other probe on each of the pins on the other end, you should only get one beep per pin (dont know the loom so making and assumption here:BigGrin:), if you get more than one beep then there's something up with the loom, if not then it is either the vehicle end, or the board end

    But saying all that thebig1 explanation makes more sense....i think ours has a direct connection as well
     
  11. Sloany

    Sloany Read Only Funster

    Joined:
    Feb 9, 2011
    Messages:
    36
    Likes Received:
    32
    Location:
    Blackpool
    The big 1 is correct, i fitted one to my van last week and it required its own dedicated 12v supply.

    Dave
     
  12. edgy

    edgy Funster

    Joined:
    Jan 25, 2011
    Messages:
    347
    Likes Received:
    421
    Location:
    bolton lancs
    Phew light at the end of the tunnel or is it power to the wire:Rofl1:
     
    • Like Like x 1
  13. Hayleylulu

    Hayleylulu

    Joined:
    Feb 17, 2008
    Messages:
    5,392
    Likes Received:
    3,889
    Location:
    Full timing in the van
    I think there's something wrong some where hope this helps you Paul :Rofl1::Rofl1::Rofl1::Rofl1:
     
    • Like Like x 1
  14. bungy

    bungy Funster

    Joined:
    Jan 24, 2010
    Messages:
    2,246
    Likes Received:
    4,127
    Location:
    Welsh marches
    can you not test it with your shiny new S3...once youve worked it out that is:Rofl1:
     
    • Like Like x 1
  15. haganap

    haganap Funster Life Member

    Joined:
    Dec 5, 2007
    Messages:
    11,065
    Likes Received:
    13,667
    Location:
    Heavan
    Ok Dave and the big 1 thanks for your advice. However, as I said, this is a system that's been fitted on other systems as per my own. It's an aftermarket fit, it's fitting instructions do not give any need for any other further wiring. Everything needed to fit it is there. As said its unplug and replug, all the other wiring is there already completed. But, big 1 what you described is a possibility but not due to the way you describe it. Is it possible that it is fused ? I was told it was fused at the cab battery with an in line 30 amp fuse. However I can not find it, there are a few fuses but none that are blown.. If there was a blown fuse it would be in line with what you are saying. The wire back to the battery is already carried out within the wiring loom that comes with the fitting. I sort of know this as the friend who sold it me fits them for swift as an aftermarket fit. However he only fits them because there is no wiring involved other than unplug and replug
     
  16. robinmclaren

    robinmclaren Read Only Funster

    Joined:
    Feb 23, 2009
    Messages:
    345
    Likes Received:
    32
    Location:
    coventry , warwickshire
    hi paul , throw away your meter and use a 12v lamp tester , this will give a lit lamp when one end to chassis and one end to suspected live terminal , meters can give weird readings on car wiring with missing neutrals . good luck . has your bessacarr got the led rear tail lights , if so there is a resitor in line to stop the light fault indicator on dash illuminating , just had a problem with this on ours
     
  17. Incamania

    Incamania Funster

    Joined:
    Jan 16, 2011
    Messages:
    45
    Likes Received:
    20
    Location:
    Lancashire
    Towbar Electrics

    Hi Paul
    Accepting the fact that the unit has worked on a similar fitting and that you believe it to be serviceable, have you considered that the 12v wiring of the vans may differ due to additional 12v equipment being installed in yours?
    My reasoning is that one of these units could be shunting the Tow Bar Circuitry, perhaps just isolating them might put you back to square 1, see if the problem disappears then reconnect them 1 at a time. Should be a simple check if all the extras have been fused.
    ATB
    Brian
     
  18. Jaws

    Jaws Funster Life Member

    Joined:
    Sep 26, 2008
    Messages:
    18,321
    Likes Received:
    21,593
    Location:
    Narrfoook
    Ummm.. Something no one has mentioned is that your base van is Can Bus Paul. ( Basic info here mate )

    It may require you to have the tan code changed in the control unit on the van..
    Speak toi Fiat ( or Pug, depending on which unit you have )
     
  19. haganap

    haganap Funster Life Member

    Joined:
    Dec 5, 2007
    Messages:
    11,065
    Likes Received:
    13,667
    Location:
    Heavan
    I have read that previously, John, again, I am informed that there is no need as it's already geared up to take the tow bar.

    I have decided to have one more look at it on Tuesday when Im off and hunt for any fuse or break in the return to Ve that the big one mentions, as the way it is performing makes sense to what he says.

    Failing that, I am going to contact an auto electrician and see if they can fix it. I am extremely disappointed to say the least. I brought it to put the bikes on to go on Holiday in 2 weeks, I expected it to plug and play, obviously it isn't as simple as that because some thing on the van refuses to allow it to be.

    Should of just gone and got one fitted :Sad::Sad:
     
  20. Jaws

    Jaws Funster Life Member

    Joined:
    Sep 26, 2008
    Messages:
    18,321
    Likes Received:
    21,593
    Location:
    Narrfoook
    Shame you are so far away mate.. Would have been happy to cast my eye over it for you.. Bored out of my brains at the moment !!

    So much so that I may even contemplate starting my winter project bike early this year !
     
Loading...

Share This Page