'46 Mercury horn wiring question

[Bruce_MO]

I'm restoring my '46 Mercury horns... it has the earlier style trumpet horns mounted on the inner fender on the driver's side. When I stripped back the original cloth loom over the wires to the horn relay at the horn mounting bracket, I was surprised to see what looks like a jumper wire soldered across the two posts (across the heavier gage yellow wire and smaller gage blue/yellow tracer wire from horn button). Third post on the relay has two clips for wires sending power "out" to energize the horns. I'm pretty sure that all the wiring was original. That jumper makes no sense to me. And the horns worked when the car was last driven before I stored it.

I'm not an expert on electrical wiring, but I was expecting 6V negative (yellow wire) into the relay, along with the blue/yellow tracer wire from the horn button, and then the two wires out of the relay to the horns. I thought when you pushed the horn button, you grounded it and completed the circuit to energize the relay and send current to the horns. It seems to me that the jumper wire would mess that all up.

Any ideas how this is supposed to work? Thanks in advance.

[V8COOPMAN]

Originally Posted by Bruce_MO

I'm restoring my '46 Mercury horns... it has the earlier style trumpet horns mounted on the inner fender on the driver's side. When I stripped back the original cloth loom over the wires to the horn relay at the horn mounting bracket, I was surprised to see what looks like a jumper wire soldered across the two posts (across the heavier gage yellow wire and smaller gage blue/yellow tracer wire from horn button). Third post on the relay has two clips for wires sending power "out" to energize the horns. I'm pretty sure that all the wiring was original. That jumper makes no sense to me. And the horns worked when the car was last driven before I stored it.

I'm not an expert on electrical wiring, but I was expecting 6V negative (yellow wire) into the relay, along with the blue/yellow tracer wire from the horn button, and then the two wires out of the relay to the horns. I thought when you pushed the horn button, you grounded it and completed the circuit to energize the relay and send current to the horns. It seems to me that the jumper wire would mess that all up.

Any ideas how this is supposed to work? Thanks in advance.

Does this image, complements of Mac VanPelt, help you any? It's 46-48 FORD, but likely the same as Merc.

Coop

[BlueSpark]

I wonder if someone bypassed the relay because they wanted to use another switch setup, maybe because the relay failed or something.

[Bruce_MO]

Coop,

Thanks for posting the schematic. I had seen it, but it’s unclear if there’s a jumper wire. I just hooked up a 6V battery charger to it and it works fine. I can hear the relay click and the horn works, so I guess the jumper wire will stay in place.

Thanks

Bruce

[BlueSpark]

I am real curious about this. The horn relay has 3 terminals, right?

One is the coil (-) that connects to the battery negative.
One is the other side of the coil which is grounded when horn button is pushed.
One is one side of the relay contact that connects to the horns.
The other side of the relay contact connects to the battery side of the coil internally to the relay.
So here are the jumper possibilities (I arbitrarily numbered the terminals):
1-2 fuse will blow as soon as horn button is pushed
2-3 fuse will blow as soon as horn button is pushed
1-3 horn will blow continuously regardless of button
So the only configuration that will work is 1-3 with a modification to the car horn button to supply 6V when the horn button is pushed rather than providing ground to the coil. But, the reason for the horn relay is to handle relatively high current which would cook the contacts of the horn button so there would need to be a higher current button or another relay.

[rotorwrench]

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Most of the horn relays back in the day had three terminals. They were generally all marked H,B, & S. H= horn or the terminal connected to the horn. Two horns would both be connected to this terminal. B= Battery or the power connection. S= Switch which is connected to the horn switch which grounds the relay and causes it to inergise and sound the two horns.

[petehoovie]

[rotorwrench]

Ford horns from that era have so connection to the ignition switch. They will sound anytime the horn switch is actuated. The relay is placed very close to the battery to get the greatest amount of amperage to the horns. They draw a lot of current.