Horn stuck on....

[bart6453]

So I got my replacement horn pack and installed it....just about crapped my pants when the horn engaged!

I cant get it to turn off...I traced the wire out of the steering column and that looks fine.

I noticed that the wiring harness has been cut and taped everywhere that horn wire leads. So I assume it is not a new problem to this truck, figured thats why it had a faulty horn pack, so it all would look right and pass inspection.

Is there a fuse panel, or block, or relay or anything somewhere in the truck that could be faulty?

Thanks,
Bart

 

[jeffhuey1n]

In the center of the steering wheel where the wires and switches all meet to make wonderful noise. best place to have a short. Unplug the electric at the horn and check the steering wheel out.

 

[bart6453]

In the center of the steering wheel where the wires and switches all meet to make wonderful noise. best place to have a short. Unplug the electric at the horn and check the steering wheel out.

I assume you are talking about the horn button.

I have disconnected the button completely and still have a direct ground, even with the wire pulled from the steering column.

 

[jeffhuey1n]

Sorry, poor humor, shouldn't happen again. Yes I meant the horn button. I just replaced my horn pack with out difficulties. If the steering wheel has been eliminated as a cause, the only other suggestion, which is sorry to say a real pain, chase the wire from the horn to the firewall. My best guess is it chaffed against the bare metal and shorted hot.

Good luck

 

[Josh]

Try kicking the front bumper. Seems to work in the movies.

Other then that, Id say the only way to know for sure is trace the entire wire or just replace the wire.

 

[cessnatwin]

Yea I believe that the horn is always hot, and you ground it at the button to come on, check the wire for frays inside the tube, I bet there is a break inside there and its rubbing. It has happened to me and it is terrible!

 

[bart6453]

Sorry, poor humor, shouldn't happen again. Yes I meant the horn button. I just replaced my horn pack with out difficulties. If the steering wheel has been eliminated as a cause, the only other suggestion, which is sorry to say a real pain, chase the wire from the horn to the firewall. My best guess is it chaffed against the bare metal and shorted hot.

Good luck

No worries...figured so much!

My concern is that someone already did chase the wire....and clearly found nothing. Looking at the loom there are no bare spots anywhere that I could see. So I was kind of wondering where it goes from the horn in to the firewall, is there some kind of a fuseblock in there? I have 24V at the horn, so it's not a dead short, or rather not in the feed side. It is on the ground wire that runs to my horn button where the short is at.

If it comes down to tracing the wire, I suppose I could just run a new dedicated ground from my horn button to the horn pack, and completely circumvent the wire harness. Essentially the ground wire could just go directly from my horn button and to the horn pack...RIGHT?

 

[cessnatwin]

yes!

 

[jeffhuey1n]

Bart
I have the wiring diagram. If you go to TM 9-2320-361-20, page FP-1 in the back of the book you should see on the left hand side the wiring for the horn. It shows two wires, one goes direct from the switch to the horn. The other goes from the horn back to a horn circuit breaker and on back into the wiring. Suggest you take alook at FP-1, it should help.
Jeff

 

[gimpyrobb]

Could also be a faulty solenoid, maybe pull the air line off and spray some air tool oil in there to help it move. Kinda like a suppository!

 

[bart6453]

Thanks for the link to the TM....I appreciate it.

No, the solenoid is fine, I have bench tested it...and the circuit is testing to ground with all the switchgear removed. A ground fault in the ground wire for sure. Frankly about the best chafed wire you could have if you have to have one in a truck.

I think I am just going to circumvent the line and run my own....make it easy on myself.

Now to fix my oil pressure gauge!

 

[Barrman]

Go to the front of the truck and look under the bumper at the end of the steering box. The wire coming out of it is the horn ground. Move it around some. You will probably get sparks. I have had several trucks with old wiring and the horn ground wire seems to always be raw at this point. Be carefull because 24 volts isn't fun to get tagged by.

If it is chaffed and bad there, go back to the steering wheel, undo all the button, tie some string to the wire and let it go down the column. Once you pull enough out the bottom to get to good insulation again, tape it up and use the string to pull things back to where they should be.