# Car Horn Question **URL:** \ **Category:** Factual Questions\ **Created:** [May 23, 2003, 1:34am UTC](https://boards.straightdope.com/t/car-horn-question/176944 "2003-05-23T01:34:35Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![syntax](https://avatars.discourse-cdn.com/v4/letter/s/41988e/32.png) [@syntax](https://boards.straightdope.com/u/syntax)\ **Post date:** [May 23, 2003, 1:34am UTC](https://boards.straightdope.com/t/car-horn-question/176944/1 "2003-05-23T01:34:35Z")
hi there, something strange has happened to my car horn. a few months ago i had a fairly pleasant sounding horn, a chord typed sound, not just a single beep. then one day whilst honking away for my friend to come out of his house, the sound changed from chord/hamrony sound to a single tone, which is most dissapointing. i have replaced the horn with the exact same one, but still no luck, can anyone shed any light on this puzzling problem? thanks in advance. ps. my car is a 1990 peugeot 405 gtxi 1.9. ---
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [May 23, 2003, 1:35am UTC](https://boards.straightdope.com/t/car-horn-question/176944/2 "2003-05-23T01:35:57Z")
Possibly a short in the wiring? ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [May 23, 2003, 1:43am UTC](https://boards.straightdope.com/t/car-horn-question/176944/3 "2003-05-23T01:43:42Z")
I’d be willing to bet you have TWO horns (hence the chord sound), try replacing the other one now. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [May 23, 2003, 1:44am UTC](https://boards.straightdope.com/t/car-horn-question/176944/4 "2003-05-23T01:44:03Z")
More like an open in the wiring. I’ll bet the horn has two wires plus a ground throught the car frame, yes? Each wire controls one transducer. Pull off each wire temporarily and test the horn to find which one is dead. Once you know that, you can begin tracing back to find the problem. It also might be in the relay. many car horns are controlled by an underdash relay that is triggered by the horn button in the steering wheel. You may want to try replacing that. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [May 23, 2003, 5:04am UTC](https://boards.straightdope.com/t/car-horn-question/176944/5 "2003-05-23T05:04:49Z")
I’ve never seen a single horn that produced two tones. I would say that either the horn you didn’t replace is faulty, or there is a wiring problem to one of the horns. ---
**Author:** ![syntax](https://avatars.discourse-cdn.com/v4/letter/s/41988e/32.png) [@syntax](https://boards.straightdope.com/u/syntax)\ **Post date:** [May 23, 2003, 11:41am UTC](https://boards.straightdope.com/t/car-horn-question/176944/6 "2003-05-23T11:41:39Z")
> [@](#): > > \*Originally posted by Q.E.D. \* > \*\*More like an open in the wiring. I’ll bet the horn has two wires plus a ground throught the car frame, yes? Each wire controls one transducer. Pull off each wire temporarily and test the horn to find which one is dead. Once you know that, you can begin tracing back to find the problem. It also might be in the relay. many car horns are controlled by an underdash relay that is triggered by the horn button in the steering wheel. You may want to try replacing that. \*\* you are correct. in the wiring, there is indeed one cable with two wires and a ground cable. the two wired cable going to the one terminal of the horn, and the ground to the other. i will test the wires today, thanks for that insight. as far as I know i only have one horn, in reply to the other poster. ---
**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\ **Post date:** [May 23, 2003, 12:20pm UTC](https://boards.straightdope.com/t/car-horn-question/176944/7 "2003-05-23T12:20:24Z")
possible some neighbour, pissed off at the inconsiderate git sounding his horn cos he can’t be ar5ed to get out of his car and knock at the door, came out and ripped your horn’s wiring out. ---
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [May 23, 2003, 12:28pm UTC](https://boards.straightdope.com/t/car-horn-question/176944/8 "2003-05-23T12:28:22Z")
> [@](#): > > \*Originally posted by pjd \* > \*\*possible some neighbour, pissed off at the inconsiderate > git sounding his horn cos he can’t be ar5ed to get out of > his car and knock at the door, came out and ripped your > horn’s wiring out. \*\* Welcome A - board **pjd**. In GQ, we _try_ not to speculate.😉 ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [May 23, 2003, 1:32pm UTC](https://boards.straightdope.com/t/car-horn-question/176944/9 "2003-05-23T13:32:28Z")
_…there is indeed one cable with two wires and a ground cable. the two wired cable going to the one terminal of the horn, and the ground to the other._ I’m sorry, but I find this confusing. What is your definition of a cable versus a wire? If I understand correctly, a ground wire goes to one terminal of the horn, and at the other terminal are two wires which are separate until they join at that terminal. The only logical explanation for this arrangement is that one of those two wires at the non-ground terminal goes on to the second horn. Otherwise there would be no sense in having two wires connected to the one terminal. Many American and Asian cars have just one wire to each horn, grounding the horns to the frame through their mounting brackets. European cars typically (always?) do not ground the horns through their brackets, but instead use a separate ground wire to a grounding terminal on the horn body. In either case, however, it is common to route the wiring for two-horn systems as I described above. The signal (switched) wire (which by the way could be either power or ground, engineer’s choice) is not split in the harness or at the relay, but goes to one horn and then continues on to the other horn. For some distance, this continuing wire is often routed in the harness parallel to the signal wire, giving the appearance of two separated wires running side by side. Your description of the problem (lost one of two tones) and of the wiring (two wires into one horn terminal) tells me there’s a second horn. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [May 23, 2003, 1:36pm UTC](https://boards.straightdope.com/t/car-horn-question/176944/10 "2003-05-23T13:36:52Z")
Above when I mentioned “one wire to each horn,” I should have said “one terminal on each horn.” ---
**Author:** ![Tuco](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tuco](https://boards.straightdope.com/u/Tuco)\ **Post date:** [May 23, 2003, 1:47pm UTC](https://boards.straightdope.com/t/car-horn-question/176944/11 "2003-05-23T13:47:40Z")
> [@](#): > > \*Originally posted by syntax \* > \*\*ps. my car is a 1990 peugeot 405 gtxi 1.9. \*\* It should have the same set up as my 1986 Peugeot 309, I’ve put the wiring diagram [here](http://www.fotango.com/p/eba00306431f00000003.jpg) , but it seems a bit blurry. If you think it could be of any use, send me an e-mail and I’ll send the full (about 1 meg) version to you. If you can make it out, the horns are the four items at the top of the page. The box just below the 2 together is the air horn compressor, and the box just below that and to the right is the horn relay.