Tow bar, Tow hitch 850

Discussion in 'Volvo 850' started by Alistair Ross, Sep 25, 2008.

  1. I would like to fit a tow bar to my 97 850 r estate....The mechanical bit is
    not a problem as I can get a bar from a scrap yard. The bit that concerns me
    is the electrics (sparks) . With these new fangled ECU gizmos and things on
    modern cars I assume wiring in extra lights is not so easy as it used to be
    in the happy days when you could splice straight into the wiring loom and
    keep your fingers crossed.

    Do any of you wizz's out there know how to do this??

    ttfn....Alistair
     
    Alistair Ross, Sep 25, 2008
    #1
  2. Alistair Ross

    Roger Mills Guest

    In an earlier contribution to this discussion,
    The only thing you need to worry about is the bulb failure warning unit
    which will get upset if it senses extra current taken by running the trailer
    lights in parallel with the car lights. There are two possible solutions:

    (a) make the connections on the battery side of the warning unit - which is
    what happens if you buy the official (expensive) Volvo trailer wiring kit.
    You can do it without the kit if you locate the unit[1] and splice into the
    relevant wires on the input side.

    (b) Buy a trailer lighting relay unit such as a PCT ZR1328A
    http://www.pct.eu.com/automotive/electrics_english_v2_frame.htm
    This takes only a miniscule current from each lighting circuit - which
    doesn't upset the bulb failure unit, and requires a heavy-duty feed from the
    battery to *actually* power the trailer lights. If you're towing a caravan
    which requires a feed via a 12S socket for fridge, battery charging etc.,
    there is another relay unit (ZR1220) which will handle that.

    [1] ISTR that on my 1999 V70 (which is basically the same car) the unit is
    under the luggage compartment floor on the LHS (when facing forward). I
    don't have the car any more so I can't go and look at it, but I think it is
    a grey box about as big as a 20 pack of cigarettes, with lots of wires going
    in and out - with a flat multi-pin plug on the input side (possibly another
    on the output - can't remember). the Volvo kit has a plug and socket which
    sandwiches between the input harness and the unit.

    HTH!
    --
    Cheers,
    Roger
    (Warwick, UK)
    ______
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    Roger Mills, Sep 25, 2008
    #2
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