FJ40 1972 Horn Issues

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Hello, I’m trying to get my horn to function properly. I tested the horn and it does work. I located the relay, pulled it and the ohms tested at 87.5. When I jump the relay top/bottom, I think pin 87 and 30 the horn works. So my guess that the problem lies in the steering column. This fj had a SBC 350 with turbo 400 trans, and what I believe to be a 70’s GM steering column with a Grant steering wheel. When I test the wire at the button I get volts bouncing all over the place. I tried running a ground to the horn button but nothing. Any ideas would be greatly appreciated. Thank!

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Yes, nothing. Does anyone know if I should be getting 12v at the button? Thanks.

According to Grant installation instructions, 1 wire systems should be connected to the center terminal on back of horn button.
 

3_puppies

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most horns use ground in the button to close a relay to make the horn sound off
no positive voltage in the column
are there horns under the hood?
is there a horn relay?
 
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most horns use ground in the button to close a relay to make the horn sound off
no positive voltage in the column
are there horns under the hood?
is there a horn relay?
Horn under the hood works and relay also works. I tried a wire grounding the button to the frame and still nothing. I’m going to try and see if I connect the middle plug on button and grounding to frame.
 
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Tap that yellow wire to the inside of the steering wheel. The horn should sound. If not, you don’t have 12v to the horn or you have a ground issue.

To me, it looks like that button does not create a closed circuit without having a ground wire. I see no way it makes contact with the steering column without one.

[EDIT]
Fixed
[/EDIT]
 
Last edited:
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The yellow wire should not have voltage, add a ground wire to the other terminal, depending on how the column was installed you may or may not be able to grab a ground on the column, the button completes the ground for the horn relay or the horn depending on how yours is wired, with or without a relay.
 
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So I tried grounding the yellow wire to the frame, nothing. So I tried grounding the pin from the connector of wire harness that goes up the steering column and nothing. Does that mean there’s an issue between the relay and harness? Jumping the relay pins does sound the horn. Thanks.
 

3_puppies

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So I tried grounding the yellow wire to the frame, nothing. So I tried grounding the pin from the connector of wire harness that goes up the steering column and nothing. Does that mean there’s an issue between the relay and harness? Jumping the relay pins does sound the horn. Thanks.

are you just grounding the relay so it closes? if so then yes, you have an issue between the column and the relay
 
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are you just grounding the relay so it closes? if so then yes, you have an issue between the column and the relay
Yes, I took a wire, grounded to frame and touched the pin the horn wire uses. Does the wire go from fuse box/relay straight to harness? Or is the harness wire come from the horn? Thanks.
 

3_puppies

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Yes, I took a wire, grounded to frame and touched the pin the horn wire uses. Does the wire go from fuse box/relay straight to harness? Or is the harness wire come from the horn? Thanks.


you need to ground the terminal that comes from the steering column, not the one to the horn
the ground from the column does not go thru the fuse box or a relay, the basic idea is to use the column as a grounding point, you press a button which makes contact between the column and the single wire, the single wire goes to the horn relay, the ground closes the relay which sends power to the horn, which is generally grounded at it's mounting point
 
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Just want to thank everyone for pointing me in the right direction. I followed the wiring and in a nest was a bare black wire which just happened to say to Horn Switch touched a bolt and the horn went off. I felt pretty dumb but can start from there. Still no luck with it on the connector but now I know where the problem lies! Thanks again.
 
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Just want to thank everyone for pointing me in the right direction. I followed the wiring and in a nest was a bare black wire which just happened to say to Horn Switch touched a bolt and the horn went off. I felt pretty dumb but can start from there. Still no luck with it on the connector but now I know where the problem lies! Thanks again.
you need to ground the terminal that comes from the steering column, not the one to the horn
the ground from the column does not go thru the fuse box or a relay, the basic idea is to use the column as a grounding point, you press a button which makes contact between the column and the single wire, the single wire goes to the horn relay, the ground closes the relay which sends power to the horn, which is generally grounded at it's mounting point
The button works but now my problem lies in between column. It has one of the old gm turn signal switches with the plate that should spin with the horn wire. Any thoughts on what I can do? Already tested button off with ground wire and used same ground when the button was on the yellow wire but no luck. Maybe the connection between turn signal switch and plate? Thanks.
 
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All fixed, turns out it was the button on turn signal switch. It wasn’t reaching the horn wire disc. Took out the spring of the button and extended. Everything works great now, thanks again everyone for the insight. Horn hasn’t worked in years. PO must not have cared.
 

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