horn works only when engine off!
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Freshman User
Joined: Jan 2009
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horn works only when engine off!
87 F250: getting ready for inspection, thought i had horn fixed by knocking some corrosion off the fuse (truck has been sitting about a year). final check before taking to inspection; found that the horn only works when engine ignition is in the "off" position, not when running or in the "on" position!
any ideas about this? btw i have a replacement column and ignition switch, still using the original wheel that had cruise control. but replacement column didn't have that. but i dont get why turning the key to on seems to de-activate the horn.
barry f
any ideas about this? btw i have a replacement column and ignition switch, still using the original wheel that had cruise control. but replacement column didn't have that. but i dont get why turning the key to on seems to de-activate the horn.
barry f
Posting Guru
Joined: Jan 2002
Posts: 1,346
Likes: 8
From: Baltimore
Here's the schematic for a 88. The 87 should be the same but the color
of the wires could be different.
When you don't have cruise control and the horn switch is depressed
12 volts from Fuse #16 which is hot at all times is supplied to the horns.
If you have cruise control, there is a Horn Relay. When
you pressed on the horn switch it applied ground to the coil
of the Horn Relay which closed the relay contacts. 12 volts from
Fuse #16 which is hot at all times then supplies 12 volts to the horns.
of the wires could be different.
When you don't have cruise control and the horn switch is depressed
12 volts from Fuse #16 which is hot at all times is supplied to the horns.
If you have cruise control, there is a Horn Relay. When
you pressed on the horn switch it applied ground to the coil
of the Horn Relay which closed the relay contacts. 12 volts from
Fuse #16 which is hot at all times then supplies 12 volts to the horns.
Thread Starter
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Freshman User
Joined: Jan 2009
Posts: 37
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thanks all.
i decided i needed to take the easy way out, since i wanted to get truck inspected before snowfall. for about $20 for button, relay circuit, wiring, i just installed a horn button on the dash.
barry
i decided i needed to take the easy way out, since i wanted to get truck inspected before snowfall. for about $20 for button, relay circuit, wiring, i just installed a horn button on the dash.
barry
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