On the horn now

[adileo]

Hi

As previously mention my horn is not working.

Today I put test light on relay. It has two hot leads and one I assume ground.

When I jump each hot to ground the horn does not blow. It, for lack of better words, shutters.

What does this tell me and what is suggested for next steps?

Thanks in advance.

[drolston]

Connect a volt meter set on the 10 volt DC scale between a bare spot on the horn itself and a good chassis ground, or the battery ground strap. Push the horn button and watch the volt meter. If it jumps, the horn ground has electrical resistance. If so, clean the horn ground where it mounts to be sure the connections have not corroded. If the horn ground is okay, touch a wire (at least 16 gauge) directly from battery to the output side of the horn relay, the wire that goes to the horn. If the horn does not blow correctly, the problem is in the horn. It will have to be disassembled so you can run some emery paper between the points to clean them. If that does not fix the problem, the windings within the horn coils may have deteriorated, in which case the horn will probably need to be replaced.

[FortyNiner]

Oops on the assumption.

There are three relay leads: horn button, the horn(s), and power (usually from the hot side of the solenoid). The horn itself is grounded (typically with the mounting but a separate ground wire can also be used).

https://www.google.com/search?q=ford...lY5VBsWohSHAM:

[adileo]

I should have mentioned the 39 has two horn pipes. I assume the two hot leads on the relay - one for each

[JSeery]

There should be three terminals on the horn relay. Power in from the starter solenoid, Ground wire to the horn button & the lead to the horn(s). Both horns should connect to the same terminal on the horn relay. The diagram if for a (-) ground system, the (+) ground diagram would be the same except the BAT terminal would be marked (-).

[petehoovie]

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Horn relay circuit:

Positive ground, of course....

[adileo]

Guys this is great. Can you tell me how I test it out?

Based on drawings I think I did it wrong.

So I tried taking a good grd jumper on firewall and connected it to horn terminal and horn sputters.

what would be next step? Remove horns and hard wire to battery!

[JSeery]

Yes

[petehoovie]

"Remove horns and hard wire to battery?" - Hold off on doing this for now.....

From your description it sounds as though the horn circuit is a high resistance to ground. Inspect/check ALL connection in the horn circuit first; especially the bullet connectors. Pull the bullet connectors apart, inspect and clean. If they're crimped, re-crimp or solder them if you can. Check the horn mountings to make sure they are making good ground contact....

[Tinker]

Pete, would there be an issue to damage the horn on straight battery? They should work on straight voltage momentarily. It'd be a quick way to narrow down the issue. If they work it'll be easier to clean everything off and decide the next move. Isn't the relay to boost voltage on short bursts?

.

[JSeery]

The normal horn wiring is basically a direct connection to the battery, so no problem using a jumper direct from the battery. Easy connection point would also be the starter solenoid battery terminal.

[Tinker]

So this could be a bad relay or horn is bad.

[JSeery]

Or the wiring. A jumper straight to the horn with the horn grounded will let you know if it's the horn. Everything else is removed from the circuit.

[Tinker]

I agree. Should be able to use 12v for a short burst.

[adileo]

Thanks guys. Here's the results.


I disconnected the 2 wires (grd and horn wire) relay. Wired grd side to good known grd on fire wall. Removed the horn terminal from relay and took horn wire (via a good jumper) over to battery touched and the battery and the horn BLEW loud.


Put horn wire back on relay and tried touching the ground relay wire to the good known grd and horn did not blow.


Is this an indication that the relay is bad?

[JSeery]

If it's not the horns, it's the relay or the wiring. Try a short jumper across the horn relay itself between the power terminal and the horn terminal. This will connect the battery via the vehicle wiring to the horn bypassing the relay. If the horns work fine it is most likely a bad relay. If horns do not work correctly it is most likely a wiring problem.

[adileo]

Thanks Jerry - horn worked with that jump - so relay is bad.

Thank you Sir!

[KGS]

Originally Posted by adileo

Thanks Jerry - horn worked with that jump - so relay is bad.

Thank you Sir!

Not necessarily. Open up the relay and check the points. Carefully open the point gap and dress them up with a points file.

[flatheadmurre]

Ground the post going to hornbutton first...if horn blows issue is in wire to horn button or contact under hornbutton....if no sound relay is prime suspect.

[tubman]

+1 on what "KGS" said. I had exactly this same problem and solution.