M35a2 horn solenoid

[mitchsc0tt0]

Hey all,
Recently had my air horn solenoid die. Checked all. Wires and verified ground was closing correctly with horn button and hot 24v at other wire. Problem is as soon as I plug in the hot wire it goes on even if I don't plug in the horn button wire from the column. I played around with it and it seems to be grounding to the brass fittings it this normal or a bad unit?

Thanks,

Mitch

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[cattlerepairman]

As you found out, the horn solenoid gets a permanently hot +24V supply and the circuit is completed by closing the ground via the horn button. If the ground wire is disconnected on the solenoid and the horn starts blaring as soon as you put the 24V lead on, the solenoid is grounding itself to the chassis - which it shouldn't be doing!
A replacement would fix that; if you are so inclined you can open the old one and see if you can fix whatever is causing the short.

If the horn blares when both connectors (Ground and 24V) are connected, the cause could also be a chafed horn wire in the steering column, most often where it exits at the bottom (where a rubber plug should be but often isn't), or a short in the horn button itself.

Wiring diagrams are in TM 9-2320-209-20-2-2

 

[glcaines]

If the horn blows when you haven't connected the wire from the horn button, the problem is almost certainly the relay.

 

[mitchsc0tt0]

Thanks all yeah it was a bad solenoid I got shipped to me.

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[jasonjc]

Mine stuck on the other day. Used some BP blaster air tool conditioner. Free it right up.