307 towbar wiring
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  1. #1
    Fellow Frogger!
    Join Date
    Nov 2010
    Lavers Hill

    Default 307 towbar wiring

    I have a 307 xs HDi wagon which I bought NEW in 2007. I got the towbar and a couple of other extras as part of the purchase deal.
    It is supposed to be the standard, dealer-fitted towbar and wiring kit.
    The towbar is a Best Bars unit and carries the Peugeot logo on an ID plate, so I am confident it is genuine.


    I am thinking of fitting reversing sensors to the car as I'm getting arthritis in the neck and have great difficulty looking over my shoulder some days. In a car park recently I gave the bumper bar a nudge against a brick wall I didn't even see. I understood that the genuine wiring kit includes a "black box" to interface the towbar wiring with the car's electronics, and one feature of the black box is that it can be wired to switch off the reverse sensors when a trailer is plugged in, to prevent false alarms. I went looking for the black box to suss out how it all would go together, and got a bit of a shock - there is no black box, there is just a length of trailer flex wired from the trailer socket to the left hand tail light wires, connected to the car's wiring with scotch-lok connectors immediately behind the tail light, with an extra wire running under the sill plate to the right hand tail light to get to the right blinker wire.
    My understanding was that this was a severe no-no, because of a risk to damaging the car's computer.

    the dealer concerned is no longer around.

    I phoned a current dealer and the tech I spoke to said that there should be a black box, but not to worry it is obviously OK and he has seen the same done on Toyota 4wds without problems. It has lasted almost 7 years with occasional trailer use so far...

    My biggest concern would be if there was a fault develop in the trailer wiring, or even inside socket at the back of the car. Could this fry the computer?

    Anyone with technical knowledge about the matter, can you advise can I leave well enough alone, or should I chase up either a genuine Pug towbar wiring kit, or even a non-genuine towbar wiring interface (relay box)?

    Last edited by simca1100; 8th November 2013 at 12:14 AM. Reason: eye can spel but carnt tipe

  2. #2
    Fellow Frogger! Psychlone's Avatar
    Join Date
    Apr 2011
    Melbourne, Australia


    I have the so-called black box in my 307. I'm not sure what it's supposed to do though. I have LED trailer lights and whenever I tow I have to switch on the headlights. If I don't then all the trailer lights flicker dimly, no idea why and sometimes I think I might be better off with direct wiring like yours. I also installed the "radar" type reversing sensor. This is a strip of metal glued to the inside of the bumper bar, a wire going to a small box of electronics, one wire to ground and one wire to the reverse light. I have also installed a switch to the last wire so when I tow I can switch off the sensor. Down side is you need to take off the bumper bar. Up side is it has worked flawlessly for 5+ years, no holes to drill and nothing showing on the outside of the car.

  3. #3
    Join Date
    Apr 2011
    Geraldton WA


    I bought a used genuine 307 tow bar off ebay, which came with wiring that'd obviously been spliced in to the harness.

    I built a relay box to drive the trailer lights properly, using low coil power 20A relays:


    That way I know I'm not going to blow the freckle out of the body computer.

  4. #4
    Join Date
    Jan 2011

    Default Tow Bar Wiring

    Hi, I fitted a tow a couple of years ago and came across this website. Actually got the relay from England off ebay. There are lots of them at varying prices so worth looking around. It has worked ok so far. Only problem I have is the power supply is taken off the auxillary jack in the rear of vehicle. The trailer lights only work when the ignition on??? If you are in Melbourne I might know someone who has them now.


    AutoSpeed - Towbar Electronics

    Universal Towbar Towing Smart 7 Way Bypass Relay For Cambus & Multiplex Wiring | eBay

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