Troubleshooting Horn

[Tinwoodsman]

I installed a new horn button kit and steering column wire today and my horn still does not work. I searched to find the TM number for trouble shooting but no luck. Will someone please tell me the TM number with trouble shooting info.

Thanks.

 

[gimpyrobb]

DO you have air pressure at the solenoid?

 

[Flyingvan911]

Do you have power to the solenoid when the horn button is pushed? Also check the connection at the bottom of the steering column, below (outside) the gearbox. My connector vibrates loose and breaks the connection so I ziptied the wires together to eliminate the strain and is has no room to slide apart.

 

[Tinwoodsman]

After installing the new button kit, I disconnected the connector at the base column, turned on the power switch and tested it with a 24V trouble light. Nothing. Then I
disconnected the two wires at the horn solenoid and turned on the power. Nothing. I read in a previous thread that the horn should blow when these wires are disconnected. The air tanks are full.

 

[tsstout]

nope.. they activate the switch (solenoid) when the connection is closed...button pushed... That allows air through the switch (solenoid)...

 

[steelandcanvas]

Check the circuit breaker up on the firewall. Pull both leads out of the breaker, check them with a VOM, one of them should be hot, if so, breaker is bad. If not, dig further back to the source. Download Peter Bog's schematic, if you haven't already.

 

[Tinwoodsman]

I will track down the circuit breaker and test it.

 

[mikey]

TM 9-2320-209-20-3-1
Section VII
7-52
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[greg2560]

Hit the solenoid with 24 volt see if it blows

 

[Tinwoodsman]

I looked over 9-2320-209-20-3-1. I is great for removal and replacement but I could not find a troubleshooting procedure. Thanks to everyone I have several things to try.

 

[doghead]

The horn solenoid should have power anytime. The horn button provides a ground for the solenoid, to activate it.

You can unplug both wires at the solenoid, and with the ignition switch on, test for voltage. One wire should have voltage. The other wire should have continuity to ground with the horn button depressed.

You also need air pressure.

 

[Tinwoodsman]

Today I pulled the wires from the solenoid and one is indeed showing 24V. The other I am not sure about. I tried leaving the one wire with 24V connected and grounding the other terminal of the solenoid and nothing happened. Not sure how to check continuity on the second terminal when depressing the horn button.

I then connected leads from a 24V power supply to the solenoid terminals and got nothings. Air tanks are full and providing air.

The two terminal solenoid I found was on the engine side of the firewall just below the main harness feed from the cabin. I checked for 24V on each terminal and got nothing.

An the answer is........

 

[doghead]

Sounds like you have a bad horn solenoid.

With the wires disconnected from it, is there continuity between the two terminals? (there should be).

 

[Tinwoodsman]

DH, are you talking continuity between the terminals of the horn solenoid once the wires are disconnected?

 

[doghead]

Yes, it's a coil inside. So there should be continuity between the two terminals on the solenoid. If not, that is one sure indicator it is bad.

 

[Tinwoodsman]

Thanks DH. Will do. Is there a good way to check the circuit breaker. The one in questions connects the 25 and 10 wires.

Thanks,

 

[Tinwoodsman]

There is no continuity between terminals of the solenoid so I will order one of those but I would like to double check the C/B before I place the order. Is there a simple test?

 

[doghead]

The CB should have continuity (and low to no ohms). Always test continuity or resistance with nothing connected and no voltage applied.

No easy way for you to test it(for function).

There should be no voltage drop out of the CB.

 

[doghead]

Just to see, I went out and measured the resistance in one of my horn solenoids.

It measured 14.8 ohms. (maybe this will be useful later on)

 

[steelandcanvas]

Hey Tin, To troubleshoot the circuit breaker, unplug both wires and check for continuity. 0 or an Ohm or two would be an appropriate reading. OL on the meter is not, replace the C/B. This will be what you need. It's probably not a bad idea to have one for a spare.
15amp