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From the photos I have seen on this forum, it appears I am dealing with non-Packard components - see attached photos.





As you can see, the wiring is a mess - I have had this car two weeks, and have made no modifications. Anyway, the horns do not sound, except when I apply power from a separate battery with the horns on the workbench. A previous owner bypassed the steering wheel horn button with one mounted under the lip of the dash.



I traced the new horn button wiring - 2 black wires - to what I believe is the horn relay, and they connect on the upper and lower right sides of the relay assembly. The red wire connected to the lower left side of the relay connects to both horns. The other black wire connected to the lower right side of the relay becomes part of the wiring harness off to the left of the relay. The other black wire connected to the upper right flange on the relay connects to what I suspect is the voltage regulator. The black wire connected to the lower right side that is routed to the left is the mystery. I have consulted my copy of the owner's manual and the wiring diagram - is there no fuse block or other protective device for the horn circuit? This is 6 volt positive ground, so I would expect perhaps that mystery wire to provide a completed circuit to energize the relay. I did give the relay case a couple thumps with the butt-end of a screwdriver to make sure it was not stuck. Maybe this relay is not wired correctly. I am reluctant to replace the relay before first knowing the way it is wired is correct. Going back to a near-stock condition would be attractive. I am just not grasping something here. Any insight would be appreciated.

Those are aftermarket horns so there is no telling exactly what is needed to have them operate. I would suggest checking the horn button function and also looking at the relay to make sure it is wired correctly.

Normally the horn button completes a circuit to ground to work a typical horn relay. Usually that aftermarket type button would have one terminal and a wire going to the relay with the ground being provided thru the case by one of the button mounting screws. Since there are two terminals and two wires on the button then you need to determine if one wire is grounded or is powered and whether pushing the button completes a ground or sends a voltage to the relay. The relays would be a different type depending on whether it needs voltage or ground but may look identical to each other. I do see a black wire connected to ground at the relay bracket but cannot tell where it is going. If you think it is going to the button, will assume it is the ground and the button completes a circuit to ground. The other wire from the button should then be on S of the relay. If you have a volt-ohm meter you might use the volt setting first and push the button to verify there is no voltage then switch to the ohm setting to check and see if it does go to ground when the button is pushed. Use the voltage setting again to check the wire which you think is going to the voltage regulator. If it does, it would probably be on the BAT terminal and voltmeter should read 6v to ground. If so that wire would go to B on the relay. If you have voltage at relay B and the switch is making a good connection to ground then if the relay is the right type and wired correctly and working, the horns should blow. If it turns out voltage is going to the button instead of ground then the wiring would be about the same but it would need a power type relay.

Here is a diagram of the typical horn circuit Packard and most other mfgs used at that time. Normally, the battery feed comes from the BAT terminal on the starter solenoid and this type horn relay needs a ground to operate. A power or voltage type relay may look identical but is wired differently inside the relay case to power the coil on those that need a voltage to operate.

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  Horn.jpg (101.58 KB)

Thanks for including a wiring diagram in your post - that immediately solved one issue. Additionally, the other end of the wire that would supply the return circuit for the relay coil is not connected to where it would allow the coil to operate. I connected it to the negative terminal on the starter switch. The horns work well. Thanks for sharing your troubleshooting expertise.