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More advice needed please.

Discussion in 'General' started by Calaber, Mar 13, 2014.

  1. Calaber

    Calaber Nil Bastardo Carborundum

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    Must be the day for Captiva questions. This is number 2. (Moved from Captiva sub-forum - nobody reads that!)

    I purchased a used factory tow bar for the beast some time back and installed it. It came with the factory wiring loom, which simply plugs into spare plugs under the boot floor.

    And the trailer lights won't work.......

    ....because Holden, in their wisdom, include a separate wiring circuit for trailers which has to be installed during manufacture, and mine obviously didn't get it. The wiring is in the boot, but no fuse is provided and the fuse socket lacks the connectors to fit one.

    The factory tow bar loom includes two relays and two multi-pin connectors. Only one connector actually plugs in, the other seems to sit there and do nothing. I can't get my hands on a factory wiring diagram, so at present there is no trailer connection.

    Question:

    Can I just disregard the factory connections and cut and connect the trailer wiring to the various tail-light wires like we did in the old days, or does the modern car with its multliple electronics and modules, demand that the factory wiring set up with relays etc, be installed?

    Anybody?
     
  2. VR38

    VR38 Well-Known Member

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    You should be able to buy the correct plug in loom for your model car, or search the wreckers.
     
  3. _R_J_K_

    _R_J_K_ Well-Known Member

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    He has the correct plug in loom, the car however can't accommodate it.
     
  4. VR38

    VR38 Well-Known Member

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    Never done a late model myself but from what I can gather there should be two components, one clips into the rear light loom for the trailer plug and the other goes to the Parking Distance Sensor Cutoff (PDC)
    There may also extra components for light failure and electric braking.
     
  5. Calaber

    Calaber Nil Bastardo Carborundum

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    The problem isn't connecting the tow bar wiring to the car wiring. The plugs are all there and connected. The problem is the fact that the wiring terminates somewhere short of the fuse block. The slot for the trailer wiring fuse is present in the fuse block but there are no connectors for the fuse to clip into. Seems bloody stupid when the wiring loom is provided in the rear compartment, but that's what they've done.

    So, to clear this one up.

    It appears I can't use the factory loom connections. Can I cut them off and wire the trailer lights up direct to the relevant tail light wires, like they used to do before electronics took over, or will the additional load on each circuit when the trailer is hooked up cause problems for the car's electrical circuits?
     
  6. VR38

    VR38 Well-Known Member

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    I can't say for sure if it will interfere with other electrics but you should be able to splice in like the good ol days just to get the lights working without overloading the lights circuits.
    You will not get the trailer light on the dash (or any associated controls) and you will get reverse sensors beeping in reverse (not that you drive far in reverse).

    What I can't understand (relevance of fuse) is why the lights don't work if you plug the trailer socket harness into the rear lights harness.
     
  7. Calaber

    Calaber Nil Bastardo Carborundum

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    I think it's crazy too, but the trailer circuit is protected by the fuse (obviously) and must also protect other circuits which aren't obvious to me. What I don't understand is why they would include the wiring loom at the rear of the car, so that the factory trailer loom just plugs in (which it did), but break the circuit by not including the fuse holders. Dumb, dumb, dumb.

    My car doesn't have reversing sensors. They came later in production. Wish it did have. I have a reversing camera kit to install, but even that looks like it will be difficult because of the work involved running the leads from the camera to the screen. I'm not sure but I don't think there is a trailer warning light, either.
     
  8. greenacc

    greenacc Searching for the billion

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    Maybe an auto electrician can retro fit the missing wiring and fuses. Failing that i think, going by what i have heard from a few slightly dodgy but experienced people is that you can splice it in and get the basic lights working on your trailer. The flash rate and a few other things may not be quite right though, and if it blows fuses or throws error codes i never reccommended doing this!
    Have you called or visited a dealer to ask?
     
  9. 426Cuda

    426Cuda SUBLIME!

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    Have you looked to see if the circuit from the trailer loom to the fuse box is connected to another fuse/circuit? Could be either on a blank fuse slot (i.e. not connected) or another circuit with a blown or missing fuse. The wiring from the trailer circuit socket forward has to terminate somewhere? It seems both illogical and counter intuitive that the loom would simply terminate part way. It's got to be there somewhere? It may be some dodgy Daewoo thing or simply to discourage owners installing themselves to keep the $ flowing.

    Hold the bus! Checked on my neighbors Captiva 5 and the dealer installed trailer light fuse is blank. Without pulling them out one by one though we have no idea which one powers the trailer lights? Note: his disables the reverse sensor when the trailer is connected.

    Hope this helps.
     
  10. VR38

    VR38 Well-Known Member

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    Trailer lights should be powered by the captivas rear loom where you unclip the loom next to the tail light and the trailer plug clips back into each end, there should be no extra need for power except for electric braking or auxiliary power (caravan 12v lighting), I would assume (not being familiar with this model car sorry) the blank trailer fuse you refer to is for this purpose and nothing to do with the lights them selves.
    they would be fuse as above, via your indicator fuse, stop light fuse and parker light fuse...
    Trailer light on the dash I assume would be to tell you the aux or brake is connected, functioning and flattering your battery if the engine is not running or similar.

    Do you have or can you get, the installation instructions for the loom you have?
     
  11. VR38

    VR38 Well-Known Member

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    Also, is there any reference to trailer plugs in the owners hand book?
     
  12. Calaber

    Calaber Nil Bastardo Carborundum

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    The Captiva is different to Holdens in the way the trailer wiring is provided for in the car. On my VY, you disconnected the tail-light loom in the boot and inserted the trailer loom between the two connectors to re-connect the taillights.

    Not the Captiva, though. It has a "sub-loom" provided under the rear floor and, in theory, you only have to plug in the trailer loom that came with the tow bar. I did this and got no results. Then, read a post in another forum where someone had struck this problem and found the missing fuse set-up. He was advised that this was necessary for the lights to work, but I agree that it is more likely to be for some auxiliary electrical circuits to trailer brakes or internal wiring.

    I don't have any wiring diagrams and I don't know that I can just walk into my Holden dealer and ask for a copy of whatever might be in the tow bar installation kit.

    It looks like a visit to an auto electrician, which I was trying to avoid (obviously). Money is always tight and this isn't on the "must do" list at present. I might just go out and have another look at the connection set-up to see if I've missed anything.

    Edit: Just poked around the connections and I'm still stuffed if I can work out what's wrong. There is still a 12 pin female plug that isn't connected to anything. FIIK....
     
    Last edited: Mar 14, 2014
  13. Macka80

    Macka80 New Member

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    Hi, did u ever solve this? Having the same issue today...
     
  14. Calaber

    Calaber Nil Bastardo Carborundum

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    Yeah, I found that a separate module needed to be purchased which fitted into the mystery plug. Never bothered buying it and traded the car some time later.
     
  15. Macka80

    Macka80 New Member

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    Spot on. Turns out the wiring loom i got with my second hand tow bar was missing the ECU (the expensive part) so had to buy this ($175) but after plugging it in all was fine.
     

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