The Stovebolt Site Forums The Shop Area The Electrical Bay Trumpet horns not working

After doing a search of the previous threads related to horns I am not finding a solution to the problem at hand.

I am trying to install some period correct trumpet horns on Sparky the ‘46 Chevy 1/2 Ton. It is a 12 volt system. The relay is 12 volt and new. Wiring to the horns is 12 gauge and new. Wire to battery is 12 gauge and new. All wiring connections have been cleaned to bare metal. The horn points have been scuffed clean. In testing the horns after installation the relay clicks as expected. The wires to the relay, according to the Eichlen product diagram are: both horn wires to the drivers side lug, battery wire to the center lug, and ground (horn button) to passenger side lug. After connecting all as described and pressing button the horn button the relay clicks as I understand it should. No sound results. Disconnecting the horn button wire and jumping the ground from the passenger side lug on the relay directly to a clean and unpainted ground strap on the engine yeilds the same no joy result. There is no spark at the horn contacts and of course no sound. What am I not understanding here?

I know nothing about 1946; however, the 47-55st horn button lead is a hot lead (the horn body needs to have a good ground)?

I would get a meter and be 100% sure you have a good ground with the negative lead of your meter (run a jumper to the ground strap or good frame connection). Put the hot lead of the meter on your horn terminal and have someone hit the horn. If you have voltage coming to the horn you need to run a ground wire either from the horn connection bolt or the sheet metal next to the horn to a known good ground. I had an issue where I thought my horn had died. I pulled it off the truck and was preparing to drill and separate the shell to get access to the guts and at the last minute decided to bench test it. I put 12v across the horn and it worked great. I then realized over time the sheet metal the horn was mounted to no longer had a good path back to ground. I ran a jumper wire from the frame to the bolt fastening the horn to the body. Horn now works great. If you don't have good voltage at the horn repeat the procedure working backwards. Check output from the relay. Then input to the relay. and keep working back to the horn button and then input to the horn button.

46Sparky, Did these horns blow before you installed them? I believe the horn button supplies ground.

Thanks guys for all the thoughts and suggestions. Worked on this more today and still no joy. I replied to each of you below thinking others afterwards might be helped with the same or similar problem.


Tim–-If I understand, the replies given in other threads to others seeking guidance in the past, correctly the horn button on the ‘46 grounds the circuit when pressed.


Dgrinnan–-I spent time today checking ground as suggested in your reply. I am uncertain I understand, “I put 12v across the horn....” I ran a separate ground wire from horn bracket to a braided ground cable on the frame/engine today. Still no joy. The horns worked good on the bench before installation. I think will remove them and retest on the bench. The relay appears to test good, if I am doing that correctly. It reads 3 ohms on the 3 (battery) lug to 5 (switch) lug and zero in all other test combinations; 1 to 3 and 1 to 5. I disconnected the wire from the horn button to the switch lug and attached a test wire from the switch lug and touched the braided ground strap when attempting a test and there is zero response, other than hearing the relay click.


SavannahDog–-Yes, the horns worked when previously bench tested. If I understand correctly the horn button does supply the ground.

SavannahDog & 46Sparky,

There is a good possibility that I also have it wrong for Advance-Design (and New Design) trucks - sorry.

Tim
At this point I’m uncertain I have it right myself. I am going to take it back to the bench and see if I can figure out why it’s not working now. It did fine on the bench before install. I am wondering if unknowingly I somehow fried the horns when I installed them on the truck? I recall seeing one of the horn contacts (points) spark slightly and momentarily back then and make a weak sound. One horn did not spark and of course resulted in no sound. That was when I started to troubleshoot their operation.
I want to get this problem corrected before installing the running boards and fenders because it’s a whole lot easier to access stuff without them in the way.

“I put 12v across the horn....” I meant I had good voltage to the terminal screw on the horn and a good ground from the horn body to ground. I basically bench tested it in place. A jumper to a known good ground and confirmed voltage to the power terminal.

These trumpet horns are a bit different design than the single, manifold horn I am also using. (Going to use a switch to toggle use of either type as needed.) The trumpet, aka Town and Country horns, don’t have two lugs at the bottom of the rear dome shaped cover. There is only a single wire on each horn. That wire connects to the drivers side terminal of the horn relay, according to the Eichlen product wiring diagram and actually is one of the things I am not understanding. That wire is not hot, according to the diagram? I don’t understand.

EUREKA!!!!!
Finally solved this problem. As suspected it was a bad ground connection. Not with the horns or directly related parts. It was the braided ground strap connection! Decided to go all the way back to square one and check the connections there after removing the horns and successfully testing them on the bench. They worked well, just as before the initial install.

So...the lesson relearned, “It’s the GROUNDS STUPID!”

Don’t you just love it when a plan comes together. Missed you at the show today.