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348 Horn Help?

Discussion in 'Technical Q&A' started by brent Lachelt, Apr 19, 2005.

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  1. brent Lachelt

    brent Lachelt Formula 3

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    #1 brent Lachelt, Apr 19, 2005
    Unfortunately I was doing some work on my 1991 348tb and mistakenly placed a wrong relay in the horn slot in the relay panel that is over the left front wheel. Now my horn won't work. It was fine and working great until that point. The relay that I put in there was # 0332 204 122 (20/30A). The relay that should have gone there is # 0332 014 113 (30A). The fuse is fine and everything else on this fuse/relay panel works fine. I ran a wire from the positive side of the battery to the horn fuse and when I touched the horn fuse connector under the fuse, the horn blew just fine. So I know the horn works. When I touched that same wire from the positive side of the battery to the horn wire coming out of the steering wheel it would spark. I believe something was damaged in the fuse/relay panel at the horn slot. At this point I don't think I want to start ripping apart the fuse panel and a new fuse/relay panel is $595. That's kind of an expensive horn. What about jumping the fuse/relay panel and using an in line 25amp fuse. However what about the relay? I need some advice on this because I don't know what colored wires are for the horn. Also I need someone to educate me on how the car is wired to get the horn to work. Example: The positive wire on the battery goes to horn compressor? then to the relay panel? then to the horn button? Seems like any easy job I just need some direction.

    Thanks,
    Brent
     
  2. Dr Tommy Cosgrove

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    #2 Dr Tommy Cosgrove, Apr 19, 2005
    This may be a stupid question but did you put the correct relay in afterwards and try it?
     
  3. brent Lachelt

    brent Lachelt Formula 3

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    #3 brent Lachelt, Apr 19, 2005
    Actually, I did. That was the first thing I tried. Was hoping that would have fixed it.
     
  4. Miltonian

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    #4 Miltonian, Apr 20, 2005
    Last edited by a moderator: Sep 7, 2017
    OK, Brent - here is my effort at explaining the workings of the 348 horn.

    The purpose of the relay is to deliver 12 volt battery power from terminal 30 to terminal 87. This is normally an "open" circuit. To close the circuit, an electromagnetic coil pulls the contacts together. This coil is activated when a circuit is completed between terminal 85 (battery power) and terminal 86 (ground through the horn switch on the steering wheel).

    You should test two things. First, make sure you have power in the position of terminals 30 and 85 on your fuse panel, using a test light. Second, you should do a quick test on your relay. Using jumper wires, hook positive power to terminal 85 and negative to terminal 86 on the relay. You should hear a "click" as the contacts close. If you have a multi-meter, you could then test to confirm that you have continuity between 30 and 87 when the contacts close.

    From the tests you did, it sounds to me like your relay is burned out.

    Edit: By the way, according the Owners Handbook, the relay in position "B" in the same fuse panel is not used. It's also a 0332014113. I can't confirm at the moment whether it's used or not on my car, it might be a spare.
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  5. brent Lachelt

    brent Lachelt Formula 3

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    #5 brent Lachelt, Apr 20, 2005
    Jeff,

    Thanks for the time you put into this. The diagram was exactly what I was looking for. I too noticed position B was an unused postion. However, in my panel it was empty, no relay there. I was hoping that this problem was just a burned out relay. The relay in postion (I think F) is for the headlights and it is also the same relay #0332014113. I tried it in the horn position and nothing happened. I put that same relay back to it's original headlight postion and it worked fine. I do have 2 new relays ordered and I'm hoping they will be at home tonight when I get there. I think the test to see if I getting power at terminal positions 30 and 85 will tell the story. When you say test light do you mean one of those sharp screwdriver like things with the light in the handle and a gound wire at the end to clip on to a ground? Jeff, if you had no power at 30 and 85 what route would you take next to get the horn to work? I'll be home tonight and will test both the relay and terminal positions 30 and 85. Will let you know what happens with those tests. Thanks so much again.
     
  6. Miltonian

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    #6 Miltonian, Apr 20, 2005
    Brent: You're correct that the problem could be that there is no power on your relay panel at terminal 30 and 85, but I don't think that's likely. The wiring diagram isn't very specific about the source of this power supply, but it definitely does not show it coming through a fuse. It doesn't seem likely that you could have "smoked" the power supply by plugging in the wrong relay, or something else would also be dead at this point. It's an easy test with a circuit tester light (the tool exactly as you described - they're cheap and very useful to have in your tool box).

    You could do some further tests with the relay unplugged. You could check that the circuit from terminal 87 on your relay panel to the compressor is good all the way by jumping power to this point on the panel (you've already checked it from the fuse to the compressor, but not from the panel to the fuse). You could rig a tester to confirm that terminal 86 on the panel goes to ground when you push the horn button, and is open otherwise.

    This should be pretty easy to diagnose.
     
  7. brent Lachelt

    brent Lachelt Formula 3

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    #7 brent Lachelt, Apr 20, 2005
    Jeff,

    Good news I have power at terminals 85 and 30. I have a new relay, but again when I put it in I get no horn. Now help me connect the dots. What do I do next? Thanks again
     
  8. brent Lachelt

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    #8 brent Lachelt, Apr 20, 2005

    OK, I took a wire from the positive side of the battery and connected to the lighted circuit tester. When I touched the circuit tester to terminal 87, the light went on, but no horn (not sure if the horn was supposed to sound at that point) Jeff you mentioned "You could rig a tester to confirm that terminal 86 on the panel goes to ground when you push the horn button, and is open otherwise". How exactly do I do this? I'm guessing this is the next test I need to run?
     
  9. Miltonian

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    #9 Miltonian, Apr 20, 2005
    Hi. Sorry, I was taking a nap (?).

    OK, you've got power on the relay board at 30 and 85, right? Stick a bent paperclip or something metal into the contacts at one of them. Attach the clip on the circuit tester to the paperclip. Push the pointy end of the tester into the contacts at terminal 86. It should NOT light up, until someone presses the horn button, then it SHOULD light up if the button produces an actual ground. It's easy to test by just pressing the pointy end of the tester to any ground point around the relay panel. You're just looking for a loop from positive to negative to light up the light.

    Another test. Take your bent paperclip and stick one end into terminal 30 or 85, and the other into terminal 87 - just for an instant, because the horn should blow immediately when you do this.

    Make sure (!) you are looking at the right terminals in the relay panel. You don't want to be jumping power at random. You can't hurt anything if you jump the correct terminals.
     
  10. brent Lachelt

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    #10 brent Lachelt, Apr 20, 2005
    OK back from dinner... should have some answers in about 15 min....
     
  11. brent Lachelt

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    #11 brent Lachelt, Apr 20, 2005
    OK, here are the results. I put a paper clip in terminal 30. Attached the light tester to the clip and then touched terminal 86 in the pointy end of the tester. No light. I then pushed the horn at the same time and still no light. I then touched the pointy end of the tester to a ground source (bolt etc.) and the tester lit up, it didn't have the horn pressed at the time and yet if I was touching a gound source it was on solid. Next I touched terminal 87 and the horn did not sound, but the tester did light up. Again by just touching 87, without pushing the horn. What do you think? Bad ground?
     
  12. Miltonian

    Miltonian F1 Veteran

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    #12 Miltonian, Apr 20, 2005
    Sounds like no ground through the horn button. Does the horn work when you jump terminal 30 to terminal 87 on the relay panel?
     
  13. brent Lachelt

    brent Lachelt Formula 3

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    #13 brent Lachelt, Apr 20, 2005
    No horn, but the test light turns on
     
  14. Miltonian

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    #14 Miltonian, Apr 20, 2005
    Hmmmm. Let's go back to post #1 for a minute. You said the horn worked when you jumped a power wire from postive to the horn fuse. This should have the same effect as jumping from from terminal 30 to 87. But now the horn does NOT sound? If the test light comes on, that means that there IS a ground through the compressor. I want to know if the horn sounds when you make a straight jump (not with the test light, with a paper clip or a jumper wire) from 30 to 87 on the relay board.
     
  15. brent Lachelt

    brent Lachelt Formula 3

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    #15 brent Lachelt, Apr 20, 2005
    Give me 5 min... I'll check with 2 paper clips
     
  16. brent Lachelt

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    #16 brent Lachelt, Apr 20, 2005
    OK I did as you asked. Horn blows!!!
     
  17. Miltonian

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    #17 Miltonian, Apr 21, 2005
    Last edited by a moderator: Sep 7, 2017
    OK, good deal. We now know that you have power to the relay, and that the circuit from the relay board to the horn compressor is OK. If we assume that your new relay is the correct one, then that pretty much means that the problem is in the grounding circuit for the electromagnetic coil in the relay, which grounds through the steering wheel.

    You know, I just learned something. I've owned that car for five years, and I never knew that there were horn buttons in the spokes!! I thought it just worked off the center button. Duh!

    OK. Pull the horn cover off the steering wheel. See anything abnormal? We might need to get into the column wiring tomorrow.
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  18. brent Lachelt

    brent Lachelt Formula 3

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    #18 brent Lachelt, Apr 21, 2005
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    Mine looked like that 4 weeks ago. I replaced it with a smaller wheel, but kept the horn button. It looks like this. Again everthing was working fine. Just the two wires going to the horn button now.
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  19. brent Lachelt

    brent Lachelt Formula 3

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    #19 brent Lachelt, Apr 21, 2005
    Need to take a quick pic of horn wires... back in 5 min.
     
  20. brent Lachelt

    brent Lachelt Formula 3

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    #20 brent Lachelt, Apr 21, 2005
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    Not the greatest pic I can try again if you need/
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  21. brent Lachelt

    brent Lachelt Formula 3

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    #21 brent Lachelt, Apr 21, 2005
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    Works better with the flash on!
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  22. brent Lachelt

    brent Lachelt Formula 3

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    #22 brent Lachelt, Apr 21, 2005
    FYI all I did was unclip those wires that feed in from the spokes. They just clip into the other wires under those black wire insulators. I did not have to move or alter the stock wires that go to the horn.
     
  23. Miltonian

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    #23 Miltonian, Apr 21, 2005
    I think there is a pretty fair chance that the problem had something to do with your new steering wheel all along, and nothing to do with your relay swap. It seems at this point that there is no question that the problem is in the grounding system at the steering wheel. Everything else checks. If there are only two wires going to your horn button, then one wire carries the signal from terminal 86, and the other grounds through the column when you push the button. Something isn't right there. Unplug the horn button and touch the wires together. Or figure out which is the wire from terminal 86, and rig up a jumper wire that goes to a known good ground. What happens?
     
  24. brent Lachelt

    brent Lachelt Formula 3

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    #24 brent Lachelt, Apr 21, 2005
    When I touch the two wires together nothing happens. Of the two wires coming to the horn the green and yellow one has to be the gound, because if you look at, it in the hub it is just rivited to the metal. That leaves the black wire as the only one that could be coming from terminal 86. So to do what you are asking " Or figure out which is the wire from terminal 86, and rig up a jumper wire that goes to a known good ground. What happens?" You mean clip a wire on the end of the black wire coming out of the steering wheel and attch the other end to a good gound? And push the horn button? Is that correct?
     
  25. Miltonian

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    #25 Miltonian, Apr 21, 2005
    Let me try a test on my 348 so I don't steer you wrong. Just a min...
     
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