Today took our 1980 240gl for a trip and happened to use the horn to salute a friend.

It made for a very short moment the usual sound, then only a "low" and not so loud sound.


I then tried the horn other times, and only hear this low sound. Repaired buttons some months ago, and they work as it should so I think is not a problem from the steering.
All parts are original from 1980, even if not used a lot they always worked normally.

Does the 240 have 2 tone horns? Can be diagnosed if something is faulty and, eventually repair?

[Edit: James posted much of the same information while I was composing this reply.]

Check fuse 2 to make sure it's not corroded by spinning it a little, or pull the fuse to make sure the ends aren't worn through from spinning.

Test the horns individually by disconnecting the other. I'm guessing one might be gone.

The contacts rarely corrode, but definitely clean them up to see if that helps. If that fails, use an ohmmeter on the black wire to check that you're getting a reasonably decent ground when the horn button is depressed. Then, with the ignition on, verify 12V on the yellow wire.

You can also try supplying your own 12V and ground to the horns individually. They will normally be noticeably louder when directly powered like that.

Note that chassis ground is supplied through the horn button (not by the horn mounting bracket). Although fairly rare, you may need to clean up the copper horn ring at the base of the steering wheel or replace a worn horn ring contact button.

Wear ear plugs or muffs as needed.

https://www.youtube.com/embed/KaK7T2x-jFY?si=r5wI4EIN6w1XnqGi SE Volvo 240 Horn Diagnosis and Repair video
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

thanks, I've already seen this video and used it to start diagnose.
I used 2 little wires connected to the horn and plugged in a battery chrger: it does works as it should.
I noticed some greenish "sludge" on the connector, so I cleaned them with contact cleaner and boom! Horn live again. Don't know if a temporary fix or if it effectively solved, but the 4-5 push I made it sounded as it should.


in our car the yellow wire is on the top connector instead of the bottom one, and so I reconnected it as it was (never removed before). Does it matter? Don't seem to have a "polarity"...

Sounds fixed to me. Just a little corrosion.

If it works then you hooked it up correctly although I recall there are no + and - markings at the terminals so it should make no difference.


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'79 242, '84 DL 2 door, '80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD

thanks!
best thing of these cars: you can fix them with minimum efforts!

Dave sez, "You can also try supplying your own 12V and ground to the horns individually." Do this.

Temporarily run a wire directly from battery + to the horn. It's the only way to know whether or not the horn is the problem. If still weak sounding run a temporary ground wire and try it again.

If you really want a horn that sounds with, "authority," get one with a strong note (think American car horn) that grounds through the mounting and use a relay. The horn button grounds the relay which closes to provide power to the horn. Get power from the hotspot on the left side of the engine compartment.


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'79 242, '84 DL 2 door, '80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD

Have you checked the FAQ? - much of the information in the FAQ pertains to ALL cars (not even just Volvos!).

Most horns work when they are grounded at the steering wheel. They always have 12 volts going to them and sound when you ground the circuit at the steering wheel. This is why horns can sound continusly sometimes in accidents that do not damage the steering wheel.

Disconnect each horn and use a meter to see which wire is hot and if it has most of 12 volts.

Reconnect the hot wire and ground the other wire - the horn should sound. Do this with each horn. This checks the horns.

If each horn sounds good, measure the resistance to ground on the ground wire for each horn when your assistant presses the horn ring. This checks the rest of the circuit. Do not mix the wires up when doing this test as you can ruin the meter movement by putting voltage to an Ohmmeter.

I would not be surprised if the horns have died of old age. There are many nice aftermarket horns, particularly if you might like a different sound.

Hi _?_,

Check for bad horn connections, get new bullet pigtails here:

https://www.prancingmoose.com/blackvinyl.html#pigtailfemale

Fill the female bullet pins with Penetrox-A to deter corrosion long term.

Good luck, Bill

The key phrase here is, "Late 240 horn Connector." The 1980 horns will have blade connections as will most replacement horns.


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'79 242, '84 DL 2 door, '80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD

So do you think only a bad connection? Thanks, First thing to investigate!

Hi,

The horn sound is made from a thin diaphragm shaped metal disc cause but magnetism from a coil of electric wire.
So yes that is how it starts. 😊

When the plate moves far enough in one direction it breaks a set of contacts inside very quickly.
The rapidness creates a frequency we can hear. It can be tuned to a certain extent but basically it’s the shape of the diaphragm and it surroundings.
Horns create a signature for car brands and size or luxury to a prospective consumer.
Much like mufflers can for the Dodge company. They have used a lot of research in that area.

If you are hearing a low tone it might be only one horn working, as there should be two on the brace.

It is a little different than hearing the sound of one hand clapping. 🤔.
That was a question in one of the Kung Fu TV series from the Master. The answer to the question was another question. What was it moving against.
It had to be Air first!
Moving that stuff is sound to our ears.

Elon Musk put a radio in the “dash shell” of a car and sent into space in a test flight.
I doubt he added speakers as extra weight or he was would have been laughed at. But then again, it was at least a smirk.


😊
Phil

So do you think only a bad connection? Thanks, First thing to investigate!