Horn Wiring Example - 66 D100

[aaronkyle]

I have been rewiring my 66 D100 with the Ron Francis wiring harness and it only supplies you with a power line going to the horn. I have a dual horn set up but don't know how it all fits together as Ron Francis doesn't give you that much information. I tried to look at the wire diagram but it doesn't paint a good picture since the new harness doesn't have the same wiring flow.

Any suggestions on how to get both of these horns working or at least one?

Both horns are dual pronged.

Thanks!

[712edf]

I have heard of the Ron Francis harness but am not familiar with any of its specifics. I am somewhat oriented with the factory set-up, or at least the ones from the mid 70's. Those IIRC were set-up to where pressing the horn button on the steering wheel would complete the GROUND leg of the circuit.

To get the horn(s) to work using the stock steering wheel button I suspect a power wire from the BAT side of the fuse box needs to go into the column & a wire coming out goes to the horn(s). I am not sure if one of the terminals on the horns themselves needs to be wired to ground. Examine the horns closing to see if either terminal has any markings such as +/-, BAT or GRND.

Bucky

[PwrWgnDrvr]

+12 from the fuse panel goes directly to one horn terminal, or +12 from the ign switch accessory terminal goes to that terminal. Depends on whether you want the horn to only work when the key is on.
The other horn terminal goes to the horn button in the column, which ground it when the button is pushed.
NO TERMINAL ON THE HORN ITSELF IS GROUNDED.
+12 DOES NOT GO INTO THE COLUMN.
For 2 horns, you simply connect the terminals of the second one to the same terminal of the first one. (parallel)

[712edf]

+12 from the fuse panel goes directly to one horn terminal, or +12 from the ign switch accessory terminal goes to that terminal. Depends on whether you want the horn to only work when the key is on.
The other horn terminal goes to the horn button in the column, which ground it when the button is pushed.
NO TERMINAL ON THE HORN ITSELF IS GROUNDED.
+12 DOES NOT GO INTO THE COLUMN.
For 2 horns, you simply connect the terminals of the second one to the same terminal of the first one. (parallel)

Does it matter which prong on the horn itself is connected to the power & which is connected to the button (ground)?

Also wasn't one horn Hi-tone & the other Lo-tone on the stock set-up or am I thinking of GM/Ford?

I think my scenario was when I attempted to wire a single prong aftermarket horn to the factory steering wheel button, which wasn't set up to provide power, only the ground.

Bucky

[nutz]

yes one should be high one low
to use a signal wire horn would need to use a relay
horn switch is ground always ...
so a 4 wire relay the control legs one would have power other to button
then the switch side would also have power then the last go to the horn
the horn must be grounded

[aaronkyle]

This is all really helpful! I'll give it a go this week and report back. I was using one of the terminals on the horn for a ground but sounds like that isn't required. Clears up my mistakes

[nutz]

if its a two wire horn
one would have to be grounded
one wire horn is grounded threw the mounting bolt

[PwrWgnDrvr]

if its a two wire horn
one would have to be grounded
one wire horn is grounded threw the mounting bolt

Two wire horn is grounded thru the horn button (switch) at the steering wheel, NEITHER TERMINAL IS GROUNDED AT THE HORN ITSELF.

[nutz]

if it has a relay that sends power to the horn then the other terminal is ground