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Technical Horn Relay

Discussion in 'The Hokey Ass Message Board' started by 57 HEAP, Jan 9, 2022.

  1. I appear to be having an issue with my horn relay. I checked 12v into the relay, but half that going out. I tested the horns, and they work. But when wired up to the horn button, the horns put out very little. Not loud and intermittent.

    Attached are two relays I have. Both perform as above. Is the relay the issue? If so, what type should I use? By that I mean specifications, amps and the like.

    Thanks.
    horn1.jpg IMG_2843.jpg
     
  2. lostone
    Joined: Oct 13, 2013
    Posts: 2,820

    lostone
    Member
    from kansas

    Sounds like it might be a ground problem either in or with the steering column. The horn button grounds so that's where I would start. Maybe check to see if the column is grounded good to either dashboard or floor board.
     
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    are you sure it's wired correctly?
     
    Crazy Steve likes this.
  4. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    I think this is how it's supposed to be connected....

    switch.jpg
     
    Hamtown Al likes this.

  5. 59Apachegail
    Joined: Apr 30, 2011
    Posts: 1,504

    59Apachegail
    Member
    from New York

    Are you using delco horns from 80s or before found in all the GMs? If so the horn itself may be the issue. Have you tried different horns? There is a vibrating disk (diaphragm) in there that vibrates and makes the sound. If that disk gets dirty/rusty or otherwise doesn’t make good internal contact it won’t work properly.

    If it is the horn I don’t recommend taking them apart. I was very lucky on some with a penetrating oil soak - sprayed down the open end. I tried taking them apart and never had much luck. There are a few YouTube videos on how to do it. You can turn that little set screw but that is tuned at the factory. You can normally pick them up on the bay for $10-$20 each depending on generation. There are also the ones with gold in them that go for like $300.
     
  6. I'm with Jim, I don't think it's wired right. You can check the relay wiring by reading between the blades on the relay. With the relay unplugged, two should read to each other, between 20 and 70 ohms if you have a meter. The third one won't read to either one and that will be the horn connection. The other two are incoming power and the wire from the horn ring/button. Try connecting the power first, if you have the wrong terminal the horns will operate but poorly. Switch terminals, the horns should stop. Connecting the horn ring to the remaining terminal should operate the horn properly.
     
    57 HEAP likes this.
  7. Wanderlust
    Joined: Oct 27, 2019
    Posts: 787

    Wanderlust

    It’s either ground to the coloumn or power to the relay ,the horn itself needs to be adequately gounded, attach a wire from the horn to neg on batt, if that doesn’t work then the horn is probably rusted and nfg
     
    Last edited: Jan 9, 2022
  8. No, I'll check that out. Thanks

    It's not the horns or ground. Horns work fine when tested with the battery. Voltage is the same at the battery and between battery and horn ground wire.
     
  9. G-son
    Joined: Dec 19, 2012
    Posts: 1,275

    G-son
    Member
    from Sweden

    Did you check that input voltage under load? The permanent, unloaded voltage may look fine, just to fall on it's face when you actually try to pull some current out, so unloaded meaurements have limited use. Resistance in the wiring feeding that point causes that.
     
  10. If you are correct, then the switch and horn are backwards.
     
  11. lostviking
    Joined: Dec 23, 2019
    Posts: 90

    lostviking

    If you use an ohm meter, you should see that one of the close together terminals reads very low resistance to the power terminal. That is the one that should be grounded to turn the relay on. Do that and measure the voltage from the power terminal to the horn, or load terminal. If that is reading half of your voltage, then the relay contacts are burnt. If not, then the problem is not with the relay.
    Relay is just an electronic switch. Shouldn't have much if any resistance. That mean nothing or very little voltage drop so long as you don't connect too big of a load and burn it's contacts.
     
  12. 24riverview
    Joined: Jan 13, 2008
    Posts: 1,052

    24riverview
    Member

    #1 is horn, #2 is switch, #3 is 12 volt supply
    Should it worry me that I knew the Standard Ignition part number for this (HR117) off the top of my head? :D

    HR117.jpg
     
    Algoma56 and Hamtown Al like this.
  13. brading
    Joined: Sep 9, 2019
    Posts: 704

    brading
    Member

    No 24riverview it always handy when guys can remember part numbers. :)
     
    Algoma56 likes this.
  14. Finally warmed up enough to check some things out.

    The relay is wired correctly and it clicks when energized. 20 ohms across the two relay terminals.

    I connected the horns directly to the battery and they work fine. When I connect the power wire to the horn wire, bypassing the relay, the horn volume is low and sound intermittent. So I think something else is the problem. The horns have a ground wire connection and that is attached to the body. At this point the steering wheel is off and I'm grounding the relay to the body. Although I haven't looked at all the connections, I usually solder all the terminals.

    What would be a good method to check the wires? What would I look for?
     
  15. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    A volt meter might help....look for low voltage everywhere in the circuit (including the ground connection at the horn), measure while the horn is "on", but not working properly.
     
  16. Not sure how to do that Jim.

    I used one lead of my meter to check the voltage going into the relay, with the opposite lead grounded and saw 12v. Same test on the voltage leaving the relay, horn button grounded, saw 6v.

    Not sure how I would check the ground. Could you explain if I have the right idea above or am I doing it wrong?
     
  17. Paul
    Joined: Aug 29, 2002
    Posts: 16,380

    Paul
    Editor

    Sounds like a faulty relay.
    Open the relay up, clean points and check action.
    I had similar issue with same relay,
    Cleaned points and put a fuse in line.
    I think I put a 30 amp fuse in mine if I remember correctly..
    You may need to clean the points at the switch/button/ring before the wheel goes on too.

     
    Jeff Norwell likes this.
  18. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    To check grounds, you can put one lead on a good ground, such as the battery negative terminal. Then put the other lead on the thing that you want to check how well it's grounded. If you get a reading like half a volt, the ground is probably OK, but if it's much more than that, like a few volts, you know the ground is flaky.

    It might be that the relay has dirty contacts, if the horns works when it's "hot" wire is connected to the battery.
     
    Paul likes this.
  19. I'll try checking the grounds as suggested.

    The relay might be the problem, but I connected the horns directly to the battery and they worked fine. But when I used the wiring harness without the relay (power wire to horn wire) the horns didn't work as well.
     
  20. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    check the wire sizes, and terminals. Horns take a significant amount of current, and anything in the circuit that introduces resistance will make them not work right.

    Try it again without the relay, and check the voltage at each stage in the circuit, relative to the battery negative terminal. If you find a significant voltage drop from one point to the next, you might have found the problem.
     
    57 HEAP likes this.
  21. Thanks for the help and suggestions all. I'm still not 100% satisfied with my results, but the horns work better with the new ground wire I added. I think the problem might be the bushing under the steering wheel needs better grounding.
     
    Hamtown Al likes this.

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