Hey guys,

I'm stumped by my horn. So the horn out of the steering wheel has a blue hot wire and a yellow/green stripe wire as well. Both go down to the turn signal connector but there is no wire coming out of the harness that attaches to yel/grn wire . So, we ran a wire from it to the horn. When I press the horn, the relay clicks, that's it. I'm stumped as to why there is no line going from the horn button out to the relay. And why would I not have horn by splicing onto the yellow/grn stripe wire directly to the horn??

The horn works, we jumped the relay and it blew.

ANy suggestions/help welcome!

 

Is on your 76 F100? I bet there is a bad ground at the rag joint.

 

There's aground at the rag joint?

 

I believe so, look for a jumper strap.

Bottom middle of diagram 1 shows blu/yel to horn relay

L/H side/middle/between the headlights of diagram 2, shows duel horns and blu/yel in and yel/grn out

 

Ok, Thanks for the diagrams. Im looking at Diagram 1 and I'm seeing the yellow blue wire going from the horn relay to the turn signal switch. However, mine is a yellow green wire and ends at the switch. So It comes out of the horn button, down the column, and then the connector has no wire to let it continue out to the relay.

So we figured this was wrong and we ran a wire from the yellow/green direct to the relay, it only clicked.

Do you thinnk theres a ground strap at the rag joint that could be jacking me up?

 

Can not confirm it an actual strap or just the horn get its ground thru there. I have read it some where on here, that is where it get grounded?

 

I did a search and you are not the only one who has said this - so I will ground it tonight. I am still wondering though why my yellow green wire stops at the turn signal harness. very odd, IMO.

 

I am pretty sure too, but no idea on the harness wiring issue. Shoot a PM to fmc400 or mikeo0o0o0 they are way better than me on this one.

 

So I got this figured out. My problem was a 78 Column in a 76 truck. The 76 did not needed a relay, the 78 did, so we bypassed the relay and I now have a horn, Thanks for the help!

 

Cool, glad you got it figured out and thanks for closing out the issue.

 

No prpblem and thanks for your help. I wonted to post about the different column in case anyone else ran into the same issue Put a 78 or later column w/turn signal switch in your 77 or ealier, and your horn wont work!

 

Actually, that's backwards. 73-77 had a horn relay, the 78-79 did not have a horn relay unless the truck had factory cruise control.
The way the 73-77 system works is:
The horn relay has three wires that go to it, yellow-constant hot, blue w/ yellow trace-ground to horn pad, yellow w/ green trace- power to horn.
The relay is constantly hot. when you press the horn pad, you're grounding the relay, this turns the relay on and energizes the yellow/green wire that goes to the horn(s).
The steering column is electrically insulated from the rest of the truck, so if you replace the rag joint, that usually eliminates the ground path for the horn switch and the horn won't work. Adding a jumper that crosses the rubber insulator disc usually restores the path.

 

That's what I had read but that did not work in my case - and I think it's because I have a steering column from a 78 in mine. There was a wire coming off the horn down to the harness but nothing at the harness.

 

Yes, that's the reason. On the 78-79, the horn pad functions like a normal switch, one wire is power in and the other wire is power out to the horn, no relay involved.
When you mix 'n match parts, sometimes you need to get creative. It becomes a case of if it works, don't mess with it.