Horn
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Horn
1979 F-150 without speed control which means there's no horn relay on this truck. Horn does not work. Jumped horn to battery successfully so the horn itself is good. Traced wire that goes to the horn back to the wire harness, from there not sure where it goes. Inspected horn pad, all looks good. However, no power to either of the leads under the horn pad. Any suggestions on how to trace this out would be appreciated. Thanks all.
Fleet Mechanic
Joined: Jan 2012
Posts: 1,668
Likes: 13
From: Saskatchewan
1979 F-150 without speed control which means there's no horn relay on this truck. Horn does not work. Jumped horn to battery successfully so the horn itself is good. Traced wire that goes to the horn back to the wire harness, from there not sure where it goes. Inspected horn pad, all looks good. However, no power to either of the leads under the horn pad. Any suggestions on how to trace this out would be appreciated. Thanks all.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
1978/79 F100/350, Bronco & Econoline with Speed Control: The horn relay plugs into the Speed Control amplifier, located adjacent to the fuse box.
Like the OP said: No Speed Control, no horn relay.
Like the OP said: No Speed Control, no horn relay.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
I don't think there is one.
It's possible the horn brushes are worn down behind the steering wheel. Pull off the steering wheel to expose the turn signal switch, and short across the two brushes that are sticking out. If the horn works that way, then the brushes must be replaced because they're no longer making contact with the steering wheel rings. Unless these are made separately, you'll have to replace the turn signal switch, or improvise.
It's possible the horn brushes are worn down behind the steering wheel. Pull off the steering wheel to expose the turn signal switch, and short across the two brushes that are sticking out. If the horn works that way, then the brushes must be replaced because they're no longer making contact with the steering wheel rings. Unless these are made separately, you'll have to replace the turn signal switch, or improvise.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
There isn't one...for sure...as there's no parts catalog listing. When I read that check the horn fuse jazz, I was pretty sure there wasn't but looked to verify.
Fleet Mechanic
Joined: Jan 2012
Posts: 1,668
Likes: 13
From: Saskatchewan
Oops I stand corrected. I thought I seen one last time I was looking at my fuse box. Funny they have an unprotected circuit.
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Hotshot
Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
I looked at the '79 wiring diagram. For a truck without speed control the circuit is actually pretty simple.
From the horn switch to the horn is a blue w/ yellow trace wire and from the switch to the power source is a yellow wire.
The sorta unusual part is the horn pulls it's power from the headlight switch
So you'll have a yellow wire from the headlight switch to the horn pad and a blue w/ yellow trace wire from the pad to the horn.
From the horn switch to the horn is a blue w/ yellow trace wire and from the switch to the power source is a yellow wire.
The sorta unusual part is the horn pulls it's power from the headlight switch
So you'll have a yellow wire from the headlight switch to the horn pad and a blue w/ yellow trace wire from the pad to the horn.
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MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
For a non-relay setup, the horn pad switches power (as opposed to ground), so there is no need for the column to actually be grounded.
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