Horn relay

[pothole]

I am having a problem getting the horn to work on my 66 F100. I was wondering if someone could tell me how the horn relay works. I tested the horn and it does work and am trying to work my way back to the horn contact spring under the steering wheel. I have three wires on the relay, Yellow, Blue w/yellow stripe, and back. I have been able to get the horn to work by connecting then yellow and black wires. I think blue w/yellow stripe head back to the fire wall. Any assistance with helping me understand how all this goes together would be greatly appreciated
Thanks
pothole

 

[DNFXDLI]

Picture incoming....the button on the steering wheel closes the coil of the relay.

 

[DNFXDLI]

 

[pothole]

horn relay

Thanks for the scans but I have a wiring diagram but don't understand the symbols within the horn relay to know what is going on. I found another confusing thing in that the wire (No, 1) at the horn contact within the steering wheel changes to a No. 2 and then back to 1 and then back to 2 on its way to the firewall harness connection. I have worked on 65 and 66 Mustangs which do not have horn relays. If someone has a better idea on how to trouble shoot a horn problem I'm receptive to anything.
Thanks
pothole

 

[DNFXDLI]

It looks to me that #1 goes all the way through.
The squiggly thing inside the relay is the coil and the XX looking thing is the contact...in this case normally open...when the coil is energized by the horn button completing the circuit, the contacts close sending power from the solenoid terminal to the horn.
Take a test light and see if there is power at the horn button on the wheel and work your way back to the relay.

 

[pothole]

horn relay

Thanks Token, I had tried testing for power at the wheel by putting the shaft of the test light down in the slot for the spring and then grounding to the steering wheel shaft. Doing this I got nothing so started from the other end making sure the horn was good. If I attach a wire clip to the yellow wire female horn relay connection and then touch the other clip to the black wire female connection the horn blows. I figure I have power at the relay. The other wire is blue w/yellow strip. jumping it to the yellow does nothing. I don't know how to test the relay to make sure it is working correctly before heading down the line.
Thanks again
pothole

 

[DNFXDLI]

To test the relay, simply take a wire from where the #1 wire attaches and ground it, that will complete the coil circuit closing the contacts.

 

[kdog]

Horn

I can't tell you on the F-100 but many older horn assemblies work by breaking or making contact through the negative side of the circuit, therefore the switch acts through the ground not the power. A relay is a relay is a relay. For simplicities sake you have a power side and a switching side. wiring diagrams for relays are generically online. Somewhere in there you should be able to isolate the circuit with an alternate power source and a test light or IDDM and then run your circuit through the relay. ( I on the other hand ran my circuit through a relay off a remote switch under the dash and didn't try to wire as original since there was no circuit on my truck left to play with. Don't know if this helps. Kel