Testing a car horn

The message from Goff Deegle contains these words:

Yes.

Ah, OK, thanks. Mine is buggered then.

Next question: presumably the purpose of the horn relay is to enable a large current to pass through the horn when a small current passes through the steering wheel terminals

Would any similar horn from any make/model of car be usable as a replacement or does the current output by the horn relay limit the number of possibilities?

The only reason for a relay in most cars is that the steering wheel contacts tend to be pretty small and flimsy, as well as having to make a 'wiping' contact with the wheel, so passing a large current would wear it out long before the expected design life of the car.

Any motor spares place will have generic disc horns that will replace pretty much any 12V negative earth horn.

You will only need a relay if you want to fit a powerful airhorn or some other strange variant. And most of those would come with their own relays etc.

The message from Goff Deegle contains these words:

Yes.

Yes.

No.

Well, probably not. Unless you're using something totally outrageus then one car's horn relay will handle sufficient current for another car's horn.

There is no amount of current output by a horn relay - it's just a switch, and has a rated current, the horn determines the amount of current. So, just replace the horn with a model that uses the same amount of current, or one which uses less. If you use a higher current horn, you'll need a fuse connecting a larger current rated relay to the battery, and hook this relays coil in place of the existing horn.

No, it's best if you plug it in to a mains socket in your garage or house. Most car horns don't operate on 12v.

Does depend on the horn - a classic VW horn won't make a noise unless you twiddle the adjuster. Frequency or something?

Thats really what the OP said if you read it.

Dave

Or, just test for continuity of the coil using a multimeter. Almost in all cases, if a horn (or a loudspeaker for that matter) fails it's the coil that has burned out, viz. an open coil circuit.

Yup.

Most relays tend to be standard types - say 20 amps - rather than made for each specific job.

Cheapest way to replace failed horns if you can't get secondhand is often air horns.

Much more likely in my experience is that the make/break contact inside has failed due to corrosion. If you can get the thing to bits without destroying it the contact can usually be cleaned up OK.

This often happens on vehicles where the horn is only used once a year at the MOT test!

Of course, it will still read open circuit with a multi-meter.

Chris

OK, accepted. I thought the switch was external or even a separate item to the horn. :)

Sadly not in this case. But a new horn is only a tenner from Halfords.

I just wonder why they're so often placed at bumper level on cars and not higher where they're less likely to get wet/corroded.

This rarely happens in London. LOL

It's not much fun driving around without a working horn. Probably illegal too. I had one prat on the M1 yesterday undertake me on the hard shoulder after he drove on from a slip road.

You think he didn't know you were there?

Who knows? At least the horn would have woken him up.

Do you have to have to post this filth here?

Goff Deegle ( snipped-for-privacy@gmail.com) gurgled happily, sounding much like they were saying :

Like Ian said - you think he didn't know you were there?

Like I said, who knows? He must have been either drunk, asleep, or retarded.

He obviously didn't know where the slip road ended and where the hard shoulder restarted.