Dual horn relay and wiring

Minor but sort of fun mod… in the German wiring diagrams I noticed a page with the schematics for a dual horn set up. It uses a relay in relay position #6, and some minor wiring changes on back of fuse panel. The only special tools needed are molex connector removal tools, 2 sizes (see this post on how I made mine). Also, you need a few of the molex connectors or you can connect to salvaged pigtails.

Here is the German wiring diagram, kinda hard to read, sorry:

And here is the stock single horn set up:

You can see that you “only” have to move the wire from connection C15 to L2, make a new connection between L2 and C15, add a ground wire to L3, and make a connection between L1 and C20. And of course, you have to add another horn and wire it up in parallel with original horn.

So what and where are those connections L1, L2, etc? They are on the back of the fuse panel, and the legend is here:

Funny how the label the L block as for horns, when the wiring diagram later show the horn wiring going to C and B blocks. The manual is not perfect 🙂

Finally, my crappy version of the modified wiring diagram (you see I have a 40 A relay in position 6, its only because that’s what I had on hand, 20 A would be fine):

For a more professional drawing of the modified wiring diagram, check out this on Michael Sullivan’s site (and have a look around the site, pretty interesting).

  1. #1 by Travis on January 24, 2012 - 10:19 am

    Interesting modification. Why do you think the factory runs wires to and from the horns, with an always hot wire at the horns? It seems to me that it would be preferable to run a single wire to the horns that is hot only when the horn button is pressed, and ground the horns to the chassis.

    • #2 by albell on January 24, 2012 - 10:52 am

      I dunno why it is a switched ground set up. I might be persuaded there is a good explanation but right now I can’t come up with one. In any case, there are more than the usual resistance spots in the current path – ie the contact ring under the steering wheel, and the contacts themselves in the horn “button”.


  2. #3 by Jaap Nauta on January 25, 2012 - 6:39 am

    I already looked into this mod some time ago, it’s a neat solution, but got stuck in finding the appropriate connector for the 4-pin L terminal. How did you solve this?
    Thanks, Jaap

    • #4 by albell on January 25, 2012 - 7:22 am


      The plastic terminal can be found on the fuse panel of Golf cabrio – first gen model (80’s on?), I was pretty excited when I discovered that 🙂
      Cut it out leaving some wire pigtails you can splice into. That is unless you have a source of new wire connectors – 2 sizes, large and small – used on the van. The small size easy to find here (molex makes an acceptable substitute), the larger size not so common. The dealer here does not sell the connectors, rather they sell pre-made pigtails. Talking to the dealer we both came to the conclusion that VW trusted techs to splice in pigtails, but not to crimp on the connectors.

      Come to think of it, if it cheap at the autowrecker, pull the entire cabrio fuse panel with lots of wire. It would be handy to have a spare.



      • #5 by Jaap on January 27, 2012 - 3:10 pm

        Thanks Alistair.
        Years ago I did the headlight upgrade, managed to get a few wire connectors, IIRC bought them at the dealer. Only the small ones left over from that job 😦
        I’ll visit some autowreckers, see if I can find the terminal; thanks for the advice 🙂

  3. #6 by Pete on November 19, 2016 - 6:30 pm

    Hi Alistair,

    I just found a new source source for the correct grey plastic 4 terminal connector block at position L

    I was keeping the individual pins in place with play dough, but this is better….. Anyway your post was what inspired me to undertake this upgrade, so thanks.

    Pete in Hamilton

  4. #7 by oldfussbudget on February 15, 2018 - 8:59 am

    They switched the ground for the same reason they do it on the interior lights, because it’s more convenient, needs fewer wires.

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