The Stovebolt Site Forums The Shop Area The Electrical Bay Try to fix my horn

Next month i have to go to the dutch DMV to get the chevy road legal. At this moment i have almost all done except the horn is not yet working.

I have the below switch/relay on the firewall. The middle is positive. The cable left is negative and the cable that I disconnected was a postive the went under my dash buth was not attched to anything and wa sjust hanging there is a spark maker. I cannot find this relay on the wiring scheme. Who knows how to fix it?

I am not sure that is wired correctly. Generally there is the positive wire from the battery (for example) that goes to one side of the relay switch, and another wire that goes from the relay to the horn. The ground wire is the trigger for the relay. For example, the horn button on the steering wheel or just a push button would ground the wire, which completes the circuit for the relay switch and send power to the hors (which are grounded to the body).

Like this

https://images.search.yahoo.com/search/images;_ylt=AwrExlRkLrFhThsA5aqJzbkF;_ylu=c2VjA3NlYXJjaARzbGsDYnV0dG9u;_ylc=X1MDOTYwNjI4NTcEX3IDMgRhY3RuA2NsawRjc3JjcHZpZAMwcGJLWlRFd0xqS2g4dXVaWWJDOXpRUHZOVEF1TndBQUFBRFNKNEFCBGZyA3lmcC10BGZyMgNzYS1ncARncHJpZANwRGV4M2pmblMuNlRuX2I4XzJDVXVBBG5fc3VnZwMwBG9yaWdpbgNpbWFnZXMuc2VhcmNoLnlhaG9vLmNvbQRwb3MDMARwcXN0cgMEcHFzdHJsAwRxc3RybAMzNgRxdWVyeQMzJTIwcGluJTIwR00lMjBob3JuJTIwcmVsYXklMjB3aXJpbmcEdF9zdG1wAzE2MzkwMDEzODA-?p=3+pin+GM+horn+relay+wiring&fr=yfp-t&fr2=sb-top-images.search&ei=UTF-8&x=wrt#id=0&iurl=https%3A%2F%2Fi.stack.imgur.com%2FmWz9g.png&action=click

Robbie 45 , what year / model ? The wiring looks "modern" so lets go with what I know. On the relay - Terminal S is wired to the Horn button. On a 1954 its 18 gauge Tan wire, attaches to a wire coming out of the steering column / horn button. The terminal B on the relay is wired to the B terminal on the voltage regulator using a 10 gauge Red wire. The H terminal on the relay is wired to the Horn (s) using a 12 gauge black wire. I've attached a photo of what it looks like on my 1954 3604 Truck and a wiring diagram for a 1954 Truck. Hope this helps.

Ron

Sorry to mention that its a 1945 model. There is no relay mentioned in the scheme. Will see if i can find the H B S stamped on the relay.

Thanks

I found this schematic online. Hope it is the right one. (It isn't q high quality but it's the only one i can find)

Mike, your link didn’t work without a copy and paste so I copied the diagram and posted it to make it easier to follow.

So i checked again. As you can see on my first post picture there is a H and a S on the cover. The middle one is not marked. But how is it possible that i have current on the middle connection and on the S ?? S should be ground right? And H should have nothing until S is grounded. Is the relay broken?

Thanks

Edit: just removed the cover. And all looks clean and correct

As you can see in the above diagram, the middle connection is for the battery positive lead. The S terminal should have power as it supplies power to the horn button. When pressed it completes the circuit to ground, pulls the plunger down on the relay and makes contact with the H terminal which supplies power to the horn/s. Ground for the relay is thru the mount to the firewall and ground to the horn is thru it’s mount or a separate ground wire.

1. There was no horn relay used in 1945 for single horn. Relay was used on dual horns. (see note)
2. Wire the relay you have according to the diagram as posted by Dragsix and reposted by Phil.
3. Depending on how you check voltage, you will see some at S when horn button is not pressed. Call it "backfeed". It's OK. Your meter/test light is providing ground.
4. The relay itself is not grounded. Does not need to be grounded.

NOTE: The dual horns, with relay, were grounded at their mounting bracket and had only one wire, which went to the relay.
The single horn, without relay, had two wires, one to hot and one to horn button. (Green51Chevy diagram)

If you have only one horn and want to use the relay. It depends on the horn you have.
Horn that is grounded by it's mounting and has only one wire, wire per diagram.
Horn with two wires, find which is the ground wire and attach to nearby chassis metal. Wire other wire per diagram.

@ bartamos. I think i just can go with 1 horn. At least i need to have something working for the DMV check in January to get a license plate for the truck. So i can remove the relay if i go to 1 horn. I think that the 2 horns that i have now are 6volt. Will they burn through if i use them on my 12v truck?

No, they will just be louder.

You can run most 6V horns on 12V if not held too long. Will be plenty loud.

Many thanks!