The horn stopped workinng. Short version of story is a guy on a cellphone cut in front of me approching a stop light. The beast needs room to stop as you all know from stock trucks. The horn work for a short blast them died but the brakes worked fine. The other guy needed to change his shorts based on the look in his eyes of the rear view mirror as the beast quickly close ground!

On to the question: positive ground 6 volt system
3 wires -- from the relay -- #1 goes up steering colum to horn button. #2 goes to horns, #3 goes to power
If I put a test light on the #3power wire or the #2horn wire the light shows power
if I put the test light on the #1horn button I get nothing.

If I jumper the #3power or the #2button to the #1horn wire I get sound.

So do I change the relay or is it the horn button. How can I tell what is dead?

Thanks for any help you electical wizards can provide.

 

Not clear how you are connecting the test light. The #1 terminal to the steering wheel grounds to close the relay, so if you connect a light from ground to #1 you're not going to get anything. (edit -- it might "look" like the horn button is being pushed and close the relay -- try grounding #1 at the relay, if the horn blows, the problem is in the button.)

If you connect the light to ground on one side and to #2 horns, without pushing the horn button, and get light, the relay is stuck "on". If it only lights when you push the horn button, that is correct.

#3 power should be Hot all the time.

 

Thanks Ross I’ll give it a try and let you know. As far as a test light I just hook one end to the frame and put the other on each terminal to see if I had power at the terminal. I have no idea what that means and it is most likely wrong and useless as I know absolutely nothing when it comes to electrical stuff!

 

In this case it is an appropriate test, when used as I described

 

Ok. It looks like the relay is stuck. It lights up and horn try’s to honk when I ground light to frame and touch the horn wire #2. #3 is life if I touch it and #1 only lites if I push horn button.
Thanks Ross you are an electrical wizard. I appreciate it. Now to find a new nos relay

 

The beast has horns again! Thank you Ross. You dioceses was right on. Tested it like you said and then replaced the relay ($14) and it works. Can’t wait sit to see the expression on the guys face that cuts me off and gets a blast from these very loud dual horns.

 

Glad to hear it was an easy fix. Ross is definitely a source when it comes to troubleshooting these old trucks.

This reminds me to start getting my 6 volt horns working. I installed a junk yard horn to get mine street legal, but have high/low horns sitting on the shelf from a '51. The last I tried , I could get them to bleet but not blast.

 

Tom the bleed is exactly what I could get one of mine to do. When I followed Ross’s instructions testing the horns (high low) were load enough in the closed garage my neighbor (duplex that the garage is a common wall) came out to see who was honking! Check your relay it’s a fast easy fix. If that doesn’t work ask Ross he will know what’s wrong. I think he should be called “The wizard of old trucks & cars”. Have fun.

 

My (6v original) horn was like that, occasional bleets but not reliable. It had dirt caked up against the diaphragm, preventing it from vibrating. I got that out, and cleaned up the contacts under the "dome" on the back, adjusted the contacts for good sound on 12v, and now it's 100%.

 

Sorry if I am hijacking this thread, but the discussion of horns and relays brings up a question.

I have read the manual, and various posts over the years regarding the use of a relay in the horn circuit. Looking over Gertie, I have never found one, or any evidence of one ever being installed.

Just reviewed the parts catalog and see that in the wiring diagram, there isn't a relay shown.

I therefore assume that if the truck is not a Deluxe, and has only the single horn mounted in front on the inner fender (behind the grille), it has no relay. If a Deluxe cab, it has the dual horns and the relay.

Correct?

 

Does that imply 12v, with the 2 horns wired in series? Or did you just make loud horns even louder and they can handle it (like the 6v starter folks keep upon conversion)?

John

 

On 48-50 trucks, only the dual-horn systems used a relay. My '52 has single horn and a relay, guess there was a change in '51? But the '51 circuit schematic doesn't show ANY horns (or the starter button, or electric wipers).

I am running my single 6v horn on 12v. With the higher voltage, the tone of the horn changes, hence the need for adjusting (shown in the manual, p. 277). They really aren't any louder. The horn seems to be OK with 12v, but it isn't something I use a lot or for a long time either.

When you run dual 6v horns on 12v, you can't really run them in series because each horn is grounded to the hood or radiator support (depending on year) thru its mounting.

 

Thanks Ross for the clarification. While I consider myself well versed in the construction of my F-2, I am not so knowledgeable of the variations in other trucks of different years. And unfortunately, the manual is somewhat vague regarding some parts and systems, the horn being one.

 

As an edit to my post on this thread (sorry hijacked):

Today I hauled my trumpet horns out of storage and proceeded to bench test them for resistance first. The coil shows 3 ohms and the resistor show 2.9 ohms which is consistent with factory values.

When using my bench power supply on both 6 VDC and 12 VDC I can't get any noise at all. It would appear the coil is not picking up. I tried using my battery charger as a source with same result.

Tomorrow I will try connecting the horm direct to battery voltage. My guess is the power supply and charger do not supply enough current (hence the need for the relay).

 

Tom it’s not a hijack you’re talking about horns and my problem was solved by the wizard. Before I posted this I disconnected the horns and tried a charger to my horns also thinking they were at fault but got nothing. I think you are correct it just doesn’t give enough power. Then I took the horn button apart on the column. Had no idea how to test so started the thread. Good luck. I know we don’t use a horn a lot but those few times come in handy