Horn Silent

[aderoy]

Strange problem, tried the horn no sound, was on the 401 so when was in a deserted area turned of my headlights (leaving just daylight running on) and the horn worked. Tried a few times, made sound. Then turned on the lights, no sound, turned off horn worked. Turned the lights on drove another hour then tried again, no sound no matter what. When I arrived home, removed and checked the fuse no problem there. Could not make any sound.When the horn worked the sound was normal and clear, if a bad ground, loose connector the sound would have been 'off' / not clean.Too dark so did not do any more checks. Ideas as to where to look?thanks in advance.

[MikeT]

Does the car have paddle shifters? If so, when driving, pull both paddles simultaneously. That should reset the circuit.

[aderoy]

Yes it is a Pulse so there are paddles. Will try on the late morning drive over to 4bucks (Starbucks).

[Utopiacdi]

Does the car have paddle shifters? If so, when driving, pull both paddles simultaneously. That should reset the circuit.

Really?? That's good to know. I would never have thought that one would have anything to do with the other but, hey....it's a Smart car Thanks Mike.

[FlossyTheSmart]

The paddle shifters and the horn all run over the same wire, each button has a differently sized resistor connected to it, so you can tell what was pressed by the voltage coming out of the steering wheel.That could also prove to be the linkage between the headlights and the horn. The headlights could somehow be pulling the voltage low enough that the car doesn't recognize what button on the wheel is being pressed, so doesn't do anything.

[aderoy]

Well did the pull both paddle shifts forward -- no change

[*]Checked the headlights, had daylight running active, then de-activated (so would not be pulling down voltage) no change.

[*]Both headlights are OEM (left side replaced in Sept)

[*]Battery was replaced 1.5 years ago, voltage good.

[*]Checked ebox dry, reseated cables. May have to pull out and open as last resort?

[*]Checked grounds inside near battery and fuse block.

Stumped in Windsor.

[MikeT]

Maybe the horn connection is corroded (at the horn)?

[tolsen]

Check if horn relay is working. The relay is inside SAM. You should hear it click.

[aderoy]

Check if horn relay is working. The relay is inside SAM. You should hear it click.

I hear the click from the relay, will double check again this morning before heading off to work. That was one item I checked but looks as if I did not place on the list. Bad.Will work on it in a heated area later in the week. From the web searches it may be a good idea to swap out the unit for a more 'vocal' one since the under pan will be lowered. Will update when there is a change.Thanks for all the suggestions.

[FlossyTheSmart]

If you can hear the relay going, that definitely narrows it down. At that point, it can really only be one of a few things (Which I'm sure you already know):-Horn itself is busted, and needs to be replaced-Contacts connecting to horn are corroded and need cleaning-A contact has come disconnected from the horn and needs to be put back on-Power or ground cable running to horn has been damaged, probably by animalsKeep us posted!

[aderoy]

The horn automagically started working early Thursday morning and had not given me any cause for concern since. So this morning lifted the front end and did a visual on the horn. Connections nice and tight, moved the terminals a few times to clean any crud that may be there. tested - horn works, voltage steady.The horn sound is clean, no warble or thin sounds (bad ground or loose connection).Scratching my head so to the root cause. Closed up the front, will test daily for the next few days (have a stretch of back road that will not annoy anyone).Thanks for all the ideas to triple check.

[Alex]

A relay can function mechanically (click!) and not electrically. Badly burnt contacts can intermittently make or not as they choose, or a particle of debris can hold them open then drop out to never return... or not.The PCB mount relays the SAM uses are readily available and easy enough to change with decent soldering experience. MB will not help, new SAM is all they can offer.

[tolsen]

Lucky my Smart has no SAM, relays are socket mounted and can be changed in second.

[aderoy]

I have good desoldering / soldering station due to the type of work I do. If the relay is bad electrically would not get the steady voltage at the terminals. Had a friend press down on horn while I measured the voltage going to the horn terminals. Even closed relays can be opened to be cleaned with diamond file or 2000 grit mylar sandpaper. Which I had not done as of yet. May get a replacement relay and swap out get because.