1972 Plymouth Duster Horns won't sound thru Horn Button

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soonercruiser

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I've been going thru this problem on the AllPAR Forum with no final resolution.

I am fixing up a 1972 Duster that just gas some racing mods; but pulled a lot of other stuff off the car that I consider necessary.
Like the horns! None there - but the pigtails were there.
Horns high 7 Low are now new, they sound great!
But...no power when horn button pressed.

Eventually discovered that they had pulled the horn relay too. Duh!
Bought a new horn relay....still no power to horns when horn button depressed.

See the diagram below of the horn relay connector:
"L" is hot!
When I jump a wire from "L" to "J", the horns sound! So, the wire (red with green tracer) to the bulkhead connector and horns is OK.

Someone had me try to jump a grounded wire to the steering wheel ground, and push the horn button - did not work.
As I said previously, the previous owner pulled a lot of stuff out. Maybe the ground wire at the column is not grounded properly?
Does anyone know what color wire that ground would be in the steering column harness?
The beautiful, expensive wiring diagram is no help here. As the horn wires is shown only going back to the "L" horn relay connector; ending there.
horn relay connector.jpg
 

Horns have constant power and the horn button actually is the earth for the relay switch on, so the horn button when pressed should have continuity to earth
 
It might not hurt to take the steering wheel off and have a look see at the switch. It could be all crudded up if the car has been sitting any. The spring under the roller might be missing and the switch is not working due to that. Just an idea.....hope you get it fixed.
 
Yeh, it's BLACK. Go over to MyMopar.com and download a factory service manual, FREE. Also on that site are aftermarket wiring diagrams, sometimes leave out details and options, but sometimes easier to follow.

But you SHOULD be able to ground it right at the relay connector
 
JDMopar said:
It might not hurt to take the steering wheel off and have a look see at the switch. It could be all crudded up if the car has been sitting any. The spring under the roller might be missing and the switch is not working due to that. Just an idea.....hope you get it fixed.
Click to expand...
Already did that and cleaned everything up.
 
Oldmanmopar said:
Screw a remote button to the dash pad
Click to expand...
That's my last resort.

67Dart273 said:
Yeh, it's BLACK. Go over to MyMopar.com and download a factory service manual, FREE. Also on that site are aftermarket wiring diagrams, sometimes leave out details and options, but sometimes easier to follow.

But you SHOULD be able to ground it right at the relay connector
Click to expand...
Service manual doesn't even have that on it!
 
soonercruiser said:
That's my last resort.


Service manual doesn't even have that on it!
Click to expand...
Doesn't have what on it?

THE BULKHEAD CONNECTOR has a well known error. The horn IS NOT YELLOW. Manual shows the horns going to "L" at the engine bay, and I thing "T" in the instrument panel diagram.

Start on page 8-147, in the 72 Plymouth manual, the horn wire is H2-16DG/R which means "H2" is the circuit, 16 is the wire size, and Dark Green/ Red tracer

Then go to 8-150, right side, to find turn signal switch connector. The very bottom terminal, H3-20BK is the horn button wire.

Then the bottom area of that page shows the relay. The far left wire, by itself, is the "key in buzzer" stuff. The three on the right hand end is the horn stuff. Violet is power from the battery. DarkGreen/Red tracer is power out to the horns, and the small BlacK (H3-20BK) is the horn button.

HornRelay.jpg


HornButton.jpg
 
Last edited:
67Dart273 said:
Doesn't have what on it?

THE BULKHEAD CONNECTOR has a well known error. The horn IS NOT YELLOW. Manual shows the horns going to "L" at the engine bay, and I thing "T" in the instrument panel diagram.

Start on page 8-147, in the 72 Plymouth manual, the horn wire is H2-16DG/R which means "H2" is the circuit, 16 is the wire size, and Dark Green/ Red tracer

Then go to 8-150, right side, to find turn signal switch connector. The very bottom terminal, H3-20BK is the horn button wire.

Then the bottom area of that page shows the relay. The far left wire, by itself, is the "key in buzzer" stuff. The three on the right hand end is the horn stuff. Violet is power from the battery. DarkGreen/Red tracer is power out to the horns, and the small BlacK (H3-20BK) is the horn button.

View attachment 1716430137

View attachment 1716430138
Click to expand...

I could swear I went thru the manual 3-4 times looking for it.
Maybe I have a not-so-good copy. But I think I didn't "connect" the bulkhead connectors to the steering wheel harness.

Thanks Much! The steering column one is the one I needed!
 
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