HORNY circuit explained

Discussion in 'How To' started by matty, Sep 17, 2013.

  1. How to sort your horn

    This covers late bays
    earlys and some crossovers are different if there is a demand i will do one for the cross-dressers

    You will need a electric multimeter you can pick a cheep one up for around £10 and a length of wire
    There is a great how to on using a meter
    http://thelatebay.com/index.php?threads/how-to-using-a-multimeter-and-testing-for-faults.4688/

    The circuit
    I have described it from the fuse to the earth point but you can skip parts the normal issues that I find with the horn are marked with a *


    Starting at fuse 11 check the fuse if the brake lights work it should be ok as it’s the same fuse

    Moving to the horn Check you have 12v on the black with yellow wire with the ignition on.

    *To test the horn itself take your piece wire and connect it from the other horn terminal (brown wire) to a good earth point with the ignition on (mind your head).

    The brown wire at the horn goes under the belly pan and up behind the fuse box along the dash to the plug and socket on the steering column that goes to the indicator switch

    [​IMG]

    To test this wire unplug the plug and connect your bit of test wire to the brown wire and take the other end of the wire to near the horn and test (using the continuity setting )between the test wire and the brown on the horn.

    The brown wire from the socket of the harness to indicator switch goes to a brass contact under the steering wheel you can just see it in the pic

    [​IMG]

    this make contact with a brass ring on the underside of the steering wheel and has a black wire connected to it, under the horn push

    Check (using the continuity setting ) between the brown on the socket and the brass spring contact
    and between the brown on the socket and the black wire under the horn push (* a common issue is the contact under the steering wheel not lined up the horn comes on when turning the wheel or not bent high enough to make contact)

    The black wire goes on to a ring mounted by 3 screws with springs and is insulated from the steering wheel base with plastic, when you pressed this ring it connects to the steering wheel

    [​IMG]

    Check the plastic that insulates the ring is ok and check (using the continuity setting) that the ring and the steering wheel are only making contact when pressed.

    The steering wheel is connected to the steering column by the big nut
    At the base of the column there is a square rubber coupler between the column and the steering box.

    Check that there is a wire linking across the coupler from a bolt on the base of the column to a bolt on the steering box

    That’s the circuit compleat
     
    Last edited: Oct 16, 2015
  2. Poptop2

    Poptop2 Moderator

    Well done Mat. Good and needed how to.
     
  3. Gonna make a comment as its easier to find the thread in the future as I want to connect my aftermarket steering wheels horn push properly as I currently have a silly button on the dash that takes forever to find when trying to let some inconsiderate tit that he's just yellow snowed me off! In fact the offender is usually a good mile away by the time I've found my horn!!!

    Thanks for the how to @matty
     
  4. Not sure if all after market ones will work on lates due to not having a contact ring on the bottom of the steering wheel
     
  5. I appreciate that chap but to have an understanding of the circuit will help me sort it :thumbsup:
     
  6. bernjb56

    bernjb56 Administrator

  7. I need to have a look at mine as I had an issue with it going off when the steering was turned. I did the top column bush and it was fine for a while but suddenly started doing it again. Its a 72/3 so early style sterring wheel and switches!
     
  8. ...and when you've tested and fixed the circuit, if your horn hasn't worked for a while don't be surprised if it issues one short barp then dies. I've had this happen on numerous occasions. The good news is my (and probably your) local motor accessories shop will sell you one for less than a tenner. The last one I got a few weeks ago was £6.99. I'll be popping in for another one on my way to work this morning. :thumbsup:
     
  9. Mine does that but not had time to look properly. One possibility is the base plate screws must be used to get the outer column equally spaced around the inner one to stop it touching. I've looked at this on mine and but something else. :(
     
  10. I didnt do anything - just started doing it so but of a mystery. In fact the steering column is a bit of a mystery tbh as ive never had it in bits and havent a clue how the horn push earths itself. Seems a strange arrangement thats destined for failure but I gusee VW knew better.
     
  11. The later ones are more sensible.
     
  12. Just been out fiddling on the bus with a number of things. Mainly trying to finally get my horn working after a lengthy diagnosis. I now know the fault. The brass contact under the steering wheel is not making contact with the brass ring itself. I turned on the ignition and then held the ring upwards with the end of my thumb, pressed the horn and PARP. She sounded.

    Question is, how to keep that sprung contact in contact. Can I simply just bend it upwards with the end of a screwdriver? I don't want to knacker it.
     
  13. yes best with the wheel off then bend it then refit the wheel
     
  14. Hi there , still a bit vague on this does a wire travel down the tube at all ,I get that you need a ground from the bottom of the tube but then what , sorry about this lol
     
  15. On a late bay there is no wire going down the tube as the inner tube acts as the wire
    The only wire is from the slipring on the steering wheel to the horn button and one across the rubber donut at the base where the tube meets the steering box.

    prototype and some crossdresser setups have a wire down the tube and the whole circuit is different
    .
     
  16. Hi , my friend as been trying all day with this horn thing , now he thinks mine may have the wrong indicator wiper attachment ,mine seems to be early indicators the paddle type ones and housing which has no brass clip to make contact with the steering wheel , the wireing is a short wire in the steering wheel nothing down the tube , so stumped again
     
  17. Mine done that when I changed to a new rubber coupling tried every thing to stop it piping when I turned the wheel gave up in the end and fitted a seperate push button ,
    Couple of weeks ago the cheap steering coupling broke noticed it had a metal webbing inside it put 2 and 2 together and realised that when I turned the wheel that the webbing must have been touching the metal work when it flexed under pressure,
    I have now brought a new vw one about £26 and wired up the horn to the steering wheel and working fine again,

    So the moral of story is don't buy cheap crap get the vw stuff,
    Steve,
     
    Dicky likes this.
  18. Brilliant that's going to come in handy when I put mine back together again. :thumbsup:
     
  19. Hi , does anyone no if there should be another insulating ring were the steering lock comes in , looking at bently manual front axle page 27 , part 11 insulating ring ? Where would I get one of these cheers paul
     
  20. Grrrrrr !!! Wish I'd read all this first, I've had more problems getting the horn to work properly than anything ele on the bus ! First of all the horn sounded when the wheel is turned hard was due to me cleverly using cap screws on the rubber coupler not bolts. Cap screw heads are taller and hit the inside of the dome at the base of the column when the shaft lifts up during hard pulling. Another "solution" was to fit a new rubber coupling as the one on it seemed to be soft and allowing excessive vertical movement. I don't know how many times I had the gearbox off before I stuck a meter across the new "rubber" to find out it's electrically conducive. Unbelieve-able ! On mine (Jan '73) the column and the shaft are both live from the horn, and there's a wire that connects them to ground through the button on the wheel. The only way the power should get to ground is down the wire and onto the box side of the rubber and not through it. Also,using penny washers under the bolt heads makes the coupling stiffer in an axial lifting mode as well.
     

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