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Discussion Starter · #1 ·
Ever since I git this car the horn didn't work. What could be the problem? Could it be a fuse?

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Could be a lot of things. The switch on the steering wheel is low amp, and that signals to a relay that is higher amperage. And of course there's a fuse somewhere. Best to start at the horn itself and work backwards with a wiring diagram to diagnose the problem.
 

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+1 on above. The horns fail more often than you might think. Test the horn with a jumper straight from +12 volts.
 

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A horn related funny story. My best friend growing up had a '70 Plymouth Fury that ended up as the "kids car". One day his sister tells me that whenever she put the turn signal on and turned the wheel to the left more than one turn, the horn would beep. I laughed, told her she must be nuts, then walked across the street with her and she showed me. Damn if she wasn't right! I pulled the wheel off and found that a mechanism in the turn signal was broken and making contact with the horn electrics.
 

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Discussion Starter · #5 ·
A horn related funny story. My best friend growing up had a '70 Plymouth Fury that ended up as the "kids car". One day his sister tells me that whenever she put the turn signal on and turned the wheel to the left more than one turn, the horn would beep. I laughed, told her she must be nuts, then walked across the street with her and she showed me. Damn if she wasn't right! I pulled the wheel off and found that a mechanism in the turn signal was broken and making contact with the horn electrics.
Lol crazy how those things can happen. Thanks for quick replies. How you i test my horn with a jumper? Do i pull of the wheel cover? Fuse?

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How you i test my horn with a jumper?
The horn is under the left front wheel well area. Use either a long piece of scrap wire or use a battery charger.

The horn is in a difficult location to access. It's kind of tucked up in there.

Doesn't make sense to me to pull the steering wheel or trouble shoot the horn relay until the horn is known working.

Besides, I can't tell you which fuse to check because I don't know the MY of your car. So check them all.
 

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Tell us what your model year is and maybe someone can point you to a wiring diagram. There should be one in your Haynes Manual.
 

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Discussion Starter · #8 ·
2002 Mustang auto v6

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For the 1999-2004 MY Mustang, the horn is powered via always on circuit F1.16.

F1.16 is located in the engine bay battery juncion box (BJB).

There is a horn relay (K33) behind the dash left hand side. Remove the relay and confirm +12 volts in terminal #2 and #5 (YE/LB).

If no power, the fuse is bad.

Use a temporary jumpper between #5 (YE/LB) and #3 (DB). This should power the horn directly.

If no sound, look for a bad horn.

If sound, then either the relay is bad or the horn switch is bad.

Measure the resistance between pin #1 (YE/LG) and a known good ground. Should be open. Press the horn button. Verify the resistance goes low. If not, there's a wiring fault or the button is bad.
 
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